Learn C Programming: Full Course Free

Do you want to learn C programming for free?, Do you want to start programming career?, Do you want to explore C programming notes online?, then this Quick short C programming course is for you. Because in this Post, I will share you Complete C programming Course.

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Introduction to Programming Language

Q. What is Language and Computer Programming Language?

Ans.=> Language is a set of instruction or rules (grammer) by the help of which we can communicate to each other. For example we use Hindi and English language for communication.

We all know that computer is an electronic dump machine. To communicate with computer we need to use programming languages or Computer Languages like c,c++,java, python,etc…

Need of Computer Languages:-

We need computer languages to develop or create programs, after combining n number of programs one software is developed. Each of the program of software performing a particular task and these programs are developed through different different programming languages or may be same.

Why we Develop Programs & Softwares?

We create programs and softwares to solve particular problem in quick manner. The working speed of computer is much faster than human being that’s why we develop softwares and programs for computer to perform any task in quick manner. 

Q. What types of applications (Software) we can develop using programming languages?

Ans=> we can develop 2 types of application using programming languages :-

i)  Standalone Applications:

the applications which must be installed in computer. This type of applications only compatible for single operating system. The application which are compatible for one operating system is not compatible for another operating system. These applications are always dependent to operating system.

For Example: 

windows operating system having there own MS word,  MS office, video player, audio player, etc

In another hand MAC operating system having their on MS word, MS office, video player, audio player, etc. We cannot use applications of one operating system into another operating system. That’s why this type of application is called standalone application.

ii) Web Application:

the applications which can be used without installing in computer is called web applications. It is not mandatory to download this type of applications in the computer. These applications are independent (Not depend) to  any operating system.

We can use these type of Applications in Any browser. There is no need to install them. standalone version of these web applications are also available but it is our choice to download them and to use them by browser.

For Example:

WhatsApp, Facebook,YouTube, Gmail, and all other social applications can be used in computer without installing and these applications are comes under web applications. In this type of application some payment transactions web applications are also include like icici bank.

Q. Why we are not using Standalone Applications in Another Operating System?

Because different different operating system having there own Extensions just like files. It is not possible to open .txt extension file in any mp3 player.because mp3 player can only understand .mp3 extension. The file having .txt  extension can only be open in any notepad. 

Just in same way we cannot use windows operating system applications in another operating system like MAC OS. Because windows application having .exe extension. 

Windows OS =>> .exe,

MAC OS =>> .dmg,

Linux OS =>> .rpm, .tar, etc.

Note: C and C++ is used to Develop only Standalone Applications thats why major parts of different different OS is Developed through C and C++. In other hand through all other Programming Languages we can develop either web application or Standalone Applications.

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1. Introduction to C

Q. What is C Programming?

Ans=> C is a programming language developed at Bell telephone laboratories in 1972 by Dennis Ritchie. It is one of the oldest and finest programming language. C programming language is reliable simple and easy to use structured programming language. Major parts of popular operating system like windows, Unix, Linux, etc are written in C. it is the most appropriate language for learning computer programming. 

C programming language is high level language and in another high level language the Syntax rule of of C language is used hence it is the basic language for all other high level languages.

Some Important Facts about C :-

• C is invented to Write Linux operating system.
• C is a successor of B language which was introduced around 1970.
• C was formalized in 1988 by the American National standard Institute (ANSI)
• Today’s most popular Linux OS and RDBMS MySQL have been written in C
• She was originally first implemented on the DEC PDP-11 computer in 1972.

Applications of C:-

C was initially used for system development work, particularly the programs that make-up the operating system. It was initially used in System Development because it produces code that runs nearly the code of assembly language. Some examples of the use of C are –

Operating Systems, Language Compilers, Assemblers, Text Editors, Print Spoolers, Network Drivers, Modern Programs, Databases, Language Interpreters

Utilities

Character Set of C Programming :-

1. Alphabets =>  A to Z, a to z.
2. Digits =>  0 to 9.
3. Special Symbols => ~ ! @ # % ^ & * ( ) _ – + : \ { } [ ] ; , < > . ? / $ “” ”

Q. Why to Learn or use C Programming

Ans=>  we learn or use C Programming Because of Some Features and Advantages of C :-

• Easy to learn
• Structured language
• It produces efficient programs
• It can handle low-level activities
• It can be compiled on a variety of computer platforms

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2.Basic Concepts of C

Variable, Constant, & Keywords in C

Variables

variables are the storage place where we can store n number of Values. We can store Data in computer through Variables. To store any value in computer we need to help variables. Through variables we can easily Store values in computer and also accessing them easily. 

Ex.=> a=2, b=’a’, c=2.5

Rules for Declaring or Naming Variables in C programming :-

1. The first character must be an alphabet or underscore(_).
2. No commas, blanks allow.
3. No special symbol other than underscore is allowed.
4. Variable names are case sensitive

Constants

An entity whose value doesn’t change is called a constant. if we change value of constant during execution of program then we get compilation error. Constants are the values which are storaged in Computer thought Variables. Means variables holds constant values in them.

Types of constant

Primarily there are 3 types of constant :-

• Integer constant =    -1,6,7,9
• Real constant =     -322.1,2.5,7.0
• Character constant = ‘a’,’$’,’@’(must be enclosed within single inverted commas).

Keywords

keywords are predefined reserved words in a programming language. these keywords help us to use the functionality of C programming. Due to their special meaning we cannot be used them for other purpose. 

There are 32 keywords available in C programming :-

***The basic structure of a C program***

All c programs have to follow a basic structure. A c program starts with the main function and executes instructions presents inside it. Each instruction terminated with a semicolon(;).

There are some basic rules which are applicable to all the c programs :-

1. Every program’s execution starts from the main function.
2. All the statements are terminated with a semi-colon.
3. Instructions are case sensitive.
4. Instructions are executed in the same order in which they are written.
5. For printing output of any C Program we Need to use predefined function of stdio.h header file Called printf( ).
6. For taking input there is one more predefined function of stdio.h header file is used called scanf().

Program to add Two numbers

/* Program to add two Numbers */               //Comment

#include<stdio.h>                              // Header File with Preprocessor

void main()                                    //Main Function

{                                              //Function Body Starting

int a,b,c;                                     //Variable Declaration

printf(“\n Enter two Numbers: “);                //Output Statement for Taking Input

scanf(“%d%d“,&a,&b);                           //Input Statement

c=a+b;                                         //Arithmetic Operation / Processing

printf(“\nSum= %d“,c);                         //Output Statement for Output Printing

}   /Function Body End

Explanation of Above Program Structure :

Comments

Comments are used to understand program in better way. Comments are not executed by Compiler. Comment are not part of program. They are used for just small note about program Writer in program to understand program clearly. We can add comment anywhere in c program after terminating Instruction using semicolon.

There are 2 types of comment available in C:-

• Single line comment: //This is a comment.
• Multi line comment:  /*This is multi line comment*/

Header files

In C programming collection of header files is called library and collection of related predefined functions is called Header files. To use any predefined function in c program we need to to declare related header file of this function before main function. 

C library is consist of n number of header files and these header files having n number of related predefined functions. Each of the function in different different header file having special functionality to perform particular task. 

There are n numbers of Preprocessors available in C and one of them is #include Preprocessor. With the help of Preprocessor #include we can Declare any header file in c program.

Ex.=> stdio.h header file contains n number of functions like printf(), scanf(), fprintf(), fscanf(), fopen(), fgets(), fputs(), etc…

Some Header files and their Functions :-

math.h => pow(), rand(), sqrt(), etc..

graphics.h => setcolor(), setbkcolor(); circle(), bar(), line(), outtextxy(), textstyle(), etc…

string.h => strlen(), strrev((, strcat(), strcpy(), strcmp(), etc…

conio.h => clrscr(), getch(), getche((, textcolor(), textbackground(), etc…

main function

main function is a predefined function in c programming. This function is compulsory to to start writing any program because C program execution is starting from main function. Without main function execution of program is not possible. 

We can also create other functions like main function but all other functions are calling directly or indirectly from main function. But main function is not calling from inside to program because it is a predefined function which is calling by operating system. We can pass arguments to main function by command line. 

Variable Declaration

we all know that to store any value in computer we need to help variables. Through variables we can easily Store values in computer and also accessing them easily. In the declaration of a variable it is mandatory to to specify its data type. In C programming some predefined primitive data types are available to declare variables. These are int, float, char, and void.

• int  variable can hold one integer value in it 
• float variable can hold one real (floating) value in it.
• char variable can hold one character value in it.
• void variable can hold one value of any type.

printf function

printf function is a predefined function of stdio.h header file. It is used in C program in 2 ways:-

1. To take value from End-user.
2. To print output of program.

Prototype or Syntax of printf function in 2 ways:-

• For Requesting input from End-user: printf(“request statement (char*string)”);

• For Printing output of program: printf(“ouput statement (char*string)”, variables list);

scanf function

scanf is also predefined function of stdio.h header file which is used to store value given by End-user through printf function. To store value in variables we need address of operator (&). We can store n number of values in n Number of variables through scanf using format specifies and using address of operator (&) before variable name.

Prototype or Syntax of scanf function:-

scanf (“formate specifiers”,&variable1, &variable2,…);

Ex=> scanf(“%d%f%c”,a,b,c);

 

***Flow Chart & Algorithm***

Flow Chart

Flow Chart is a Pictorial or Diagrammatic Representation of Institutions of programs. With the help of flowchart we can easily understand flow of any program. flowchart uses various symbols to represent different operations involved in the solution of a program.

Following symbols are used to draw flow Chart of any program :-

Algorithm

Algorithm is a set of instruction to perform a given task in a definite time, written in normal English language is known as algorithm. Algorithm is a step-by-step procedure which define flow of execution of instructions one by one to produce desired output.

 

Characteristics of an Algorithm:

• Unambiguous:- All the Steps Should be Clear and lead to be one meaning.
• Input:- should have 0 or more well defined inputs 
• Output:- should have 1 or more well defined outputs.
• finiteness:- must be terminated after a finite number of steps.
• Feasibility:- Algorithm Should be Correct with Available Resources.
• Independent:- it should be independent of any programming language.

***Flow of Program in C***

Step 1: C program (source code) is sent to preprocessor first. The preprocessor generates an expanded source code.

Step 2: Expanded source code is sent to compiler which compiles the code and converts it into assembly code.

Step 3: The assembly code is sent to assembler which assembles the code and converts it into object code. (.o or .obj).

Step 4: The object code is sent to linker which links it to the library such as header files. Then it is converted into executable code. (.exe)

Step 5: The executable code is sent to loader which loads it into memory and then it is executed. After execution, output is sent to console.

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3. Data Types in C

What is Data Types? 

data type is nothing but it is a representation of a data. In the declaration of any variable it is mandatory to specify its data type.

Syntax of Data type:- data_type variable_name;

Ex.=>         int a;

It represents two things:-

• how much memory is required to allocate for variable.
• second is what type of data is allowed to store in a particular variable.

For example=> In “int a” variable integer data type is allowed and it required 2 or 4 bytes for memory allocation.

 

Classifications of Data Types in C

Premitive Data Type

• int
  • short int : 2 bytes memory required
    • signed short :  -32768 to 32767
    • unsigned short :  0 to 65535
  • int : 2 or 4 bytes memory required
    • signed int : -2,147,483,648 to 2,147,483,647
    • unsigned int : 0 to 4,294,967,295
  • long int : 4 bytes memory required
    • signed long int : -9223372036854775808 to 9223372036854775807
    • unsigned long int : 0 to 18446744073709551615

• float 
  • loat : 4 bytes memory required  [1.2E-38 to 3.4E+38]
  • double : 8 bytes memory required  [2.3E-308 to 1.7E+308]
  • long double : 10 bytes memory required  [2.3E-308 to 1.7E+308]

• char : 1 bytes memory required
  • signed : -128 to 127
  • unsigned : 0 to 255

• Derived Data Type
  • Array
  • string
  • function
  • pointer

Some Important Questions about Char Data Type :-

Q. What is ASCII ?

Ans=> ASCII stands for American Standard Code for International Interchange. This ASCII System Consist of Total 256 (0 to 255) Characters. Through ASCII System we can Easily Access Characters in Computer. ASCII System Having Number from 0 to 255 for Each if the Character. This system is Applied for All Programming Languages.

 

Q. Why Char Data Type Range or Limit represent in integer?

Ans=> Because we are representing a character using Character system Called ASCII. ASCII Consist of total 256 (0 to 255) character. Due to which each character having perticular number. We Can Say that it is a Predefined Enumeration of All Characters in ASCII for All Computer Programming Languages.

 

Q. Why Any Character Required 1 byte memory in Computer?

Ans=> character Required 1 Byte memory for Allocation Because total characters in any programming language is definitely not more than 256. Means 256 is equal to 2^8 and 2^8  is 1 byte. That’s why one character Required 1 Byte memory in Computer.

 

***limits.h Header File***

Q. How to determine limits of data types in C programming?

Ans=> we can determine limits of data type through predefined global variables of “limits.h” header file. limits.h header file contains n number of predefined global variables. They are also called macros of limit.h header file. 

All these n number of global variables of limits.h having Constant values means we cannot modify them. 

All these predefined global variables of limits.h header file are as follows:-

***sizeof() operator***

Q. What is sizeof operator and what is the use of it in C programming?

Ans=> size of operator is a unary operator which is used to determine the size of any operand. It returns this size of a variable. It can be applied to any data type like int, float, char, pointer, structure, typedef, union, etc.

Syntax or Prototype :- int sizeof(operand or data type)

Ex. => sizeof(a) , sizeof(int), sizeof(struct emp), sizeof(arr), sizeof(str).

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4.Instructions in C

Q. What is Instructions in C?

Ans.=> Instructions are the commands  given to program for compiler to do certain specific tasks. Without instructions there is no programming language. Each of the statement of any program is part of instructions. 

There are three types of instructions available in C programming:-

1. Type Declaration Instruction : this instruction is used to declare data type of variables. We all know that before writing any variable in program it is mandatory to to specify its data type.
2. Arithmetic Instructions: arithmetic instructions are those statements of c program by the help of which program perform mathematical operations like multiplication, addition, substraction, division, etc. To perform mathematical operations in C program we need some operators (+, -, *, /, %).
3. Control Instructions: control instructions are those predefined statements in C program which are used to perform Special tasks like decision making. On the basis of of different different Special tasks control instructions are further classified into four types :-

• • Sequence control instruction: sequence control instruction ensure that the C program is executed in the same order in which they written. 
  • Decision Control Instruction: Decision control Instructions allow the computer to take a decision as to which instruction is to be executed next. Decision control instruction works on the basis of Given Condition (true/false).

Decision control instructions includes:- 

• • Loop Control Instructions: Loop control statements in C are used to perform looping operations until the given condition is true. Control comes out of the loop statements once condition becomes false. There are 3 types of loop control statements in C:-

        i) while loop: In this Loop block keeps executing as long as the condition is true. It will be terminate after condition become false. It check the condition before executing the loop body. We can also use Nested while loop according to the requirement. “If the condition never becomes false, the while loop keeps getting executed. Such a loop is known as an infinite loop“.

Syntax:
while(condition) {
statement(s);
}

Example:
int i=0; //initialisation
while (i<10){
printf(“The value of i is %d”,i); i++;
}

Flow Chart of while Loop:

ii) do while loop: Do-while loop works very similer to while loop. But the main difference between while and do-while loop is that “while loop first check the condition &then execute block” and “do-while first executes the block & then checks the condition. do while loop execute at least once.

syntax of do-while: 

do {

statement(s);

}while(condition)

Flow chart of do-while loop:

iii) for loop: This Loop is also works same as while loop but only syntax is Different. while and do-while only takes condition for working but for loop taking 2 arguments along with Condition, first is initialisation, second is condition, and third one is increment or decrement operator. 

syntax: 

for ( init; condition; increment or decrement operators) {

   statement(s);

}

Example: 

for(i=0; i<3; i++)

{

printf(“%d”,i);

printf(“\n”);

}

Flow chart of for loop:

4. Case Control Instructions: The statements which are used to execute only specific block of statements in a series of blocks are called case control Instructions.

                There are 4 Case Control Instructions available in c:-

                i) switch: Switch case statements are used to execute only specific case statements based on the switch expression. 

          Syntax=>

     switch (expression)

{

     case label1:   statements;

                           break;

     case label2:   statements;

                           break;

     case label3:   statements;

                           break;

     default:      statements;

                           break;

}

Flow chart of switch: 

        ii) break: Break statement is used to terminate the while loops, switch case loops and for loops from the subsequent execution. Whatever the condition loop is terminated after using break statement.

Syntax: break;

Example: 

for (i=0; i<1000; i++){

printf(“%d,”,i);

if (i==5){

break;

}

}

 

Output: 1,2,3,4,5

Flow chart of break:

      iii) continue: Continue statement is used to continue the next iteration of for loop, while loop and do-while loops. Whatever the statements below continue will skip and control comes to next iteration of loop. 

Syntax: continue;

Example:

  for(i=0;i<10;i++)

   {

     if(i==5 || i==6)

     {

              continue;

     }

     printf(“%d “,i);

   }

Output: 0,1,2,3,4,7,8,9

Flow Chart: 

iv) goto: this case control statement is used to move control of program to perticular  statement. goto statement is used to transfer the normal flow of a program to the specified label in the program means control move to perticular statement where we want. we can say that goto statement is used for customise flow of Program according to us. it is used for unconditional jump to labled statement.

Syntax: 

goto label;

..

.

label: statement;

flow chart of goto:

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5. Operators in C

 

Q. What are Operators in C Programming?

Ans=> operators are the special symbols that tells the compiler to perform specific mathematical or logical operations.

Types of Operators in C

On the basis of different different functionality, operators are classified into 6 type in C programming:-

1. Arithmetic Operators :-

( int a= 10, b=20;)

 

Modify Operators in C 

Modify Operators are also called unary operator because they perform operation on single operands at a time.

There are 2 types of modify Operators available in C :-

• Increment Operator: used to increase integer value by one.

        There are 2 types of increment:-

         i) pre-increment: printing value after increment.

         ii) post-increment: printing value before increment.

• Decrement Operator: used to decrease integer value by one.

       There are 2 types of decrement:-

         i) pre-decrement: printing value after decrement.

         ii) post-decrement: printing value before decrement.

Process of execution of modify Operators in C program step by step:-

Step1:  Pre-increment / Pre-decrement

Step2:  Substitution

Step3:  Evaluation

Step4:  Assignment

Step5:  Post-increment / Post-decrement

2. Relational Operators:

(int a=10, b=20;)

3. Logical Operators:

(int a=1, b=0)

4. Bitwise Operators:

In arithmetic-logic unit (which is within the CPU), mathematical operations like: addition, subtraction, multiplication and division are done in bit-level. To perform bit-level operations in C programming, bitwise operators are used. 

There are 6 bitwise Operators available in c programming :-

• strcmp function first compare the length of 2 strings. According to condition it will give output but if the length of both strings are equal than it compare one by one character of both strings.
• Whenever it found any mismatch character than it will Compare both characters ASCII Value and according to condition it return value.
• Now if all the characters of both strings are same than it will return 0.

• When a program is terminated after once running, the entire data is lost. Storing in a file will preserve your data even if the program terminates.
• If you have to enter a large number of data, it will take a lot of time to enter them all. However, if you have a file containing all the data, you can easily access the contents of the file using a few commands in C.
• You can easily move your data from one computer to another without any changes though files.

Q. What is File Handling or File I/O?

Ans=> file handling means all the activities which are perform by program is stored into a file and accessing that information at the time of requirement is called file handling or FILE I/O.

In simple word we can say that storing the information into the file and accessing that information at the time of requirement through some functions is called file handling.

Q. What is FILE Pointer?

Ans=> If we want to work with file we need to use file pointer through with we can hold the base address of file and access it into RAM. After that we can perform some operations like opening, reading, writting, etc. Basically file pointer is a communication way b/w program & file.

Syntax of file pointer:  FILE *<identity>;

Declaration: FILE *fptr;

***Basic File Operations In C Programming***

There are 4 basic operations that can be performed on any files in C programming language. They are,

• Opening/Creating a file
• Closing a file
• Reading a file
• Writing in a file

Stdio.h header file functions are used in File Handling

1.Opening/Creating a File:-

fopen() => this is the most important function which is used to open a file in different modes like write mode, read mode, append mode, etc. Return type of this function is FILE poinetr.

Syntax:  FILE* fopen(“file name”https://dheeraj-patidar.blogspot.com/2022/07/,”mode”);

Declaration: fptr=fopen (“example.txt”https://dheeraj-patidar.blogspot.com/2022/07/,”r”);;

Here fopen function is taking two arguments, one is file name (like “file1.txt”) and second is in which mode you want to open file like read, write, etc.

On success, it open the file & return the address of file.

On failure, it returns NULL Pointer.

Program for better understanding:-

***Opening Modes in FILE I/O***

2. Closing a File:-

fclose () => fclose() function is used to closes the opening file. 

Syntax: int fclose(FILE *fptr);

Declaration: fclose(fp);

It is taking one argument which is file pointer pointing to that file. 

This function returns zero if the file is successfully closed. On failure, EOF is returned.

3. Reading a file:-

For reading file 2 Predefine functions are used:-

fgetc() => this function is used to read file character by character. It is taking one character at time from file. We use loop for Collecting data by fgetc and it will stop Collecting characters when it reaches EOF (End of the file). EOF returns -1.

        Syntax: int fgetc(FILE *fptr);

        Declaration: fgetc(fptr);

It is taking one argument which is file pointer  pointing to that file. 

fscanf() => this function is used to read number from file. 

Syntax: fscanf(file ptr, “format specifier”,var. Address);

        Declaration: fscanf(fptr, “%d”,&num);

This function is taking 3 arguments, first is file pointer, second is formate specifiers, 3rd is address of a variable.

4. Writing a file:-

For Writing file we use 2 functions:-

fprintf() => this function is used to write data into any file. 

Syntax: fprintf(file pointer, “formate specifiers”, variables);

 Declaration: fprintf(fptr, “Number is %d”, num);

fputc() => this function is used to write character by character into file. 

Syntax: fputc(“character”,fptr);

Declaration:  fputc(“T.”, fptr);

Note:- There are n number of predefined functions are used in file handling concept. All above Functions are most useful.

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14. typedef

Q. What is typedef?

Ans=> 

• In C programming, typedef is a keyword which is used to give a name to any dataType in a program. In simple word we can say that typedef keyword is used to create duplicate name or Alias name of any data type.
• typedef is a user defined data type.
• With the help of typedef keyword we can give dublicate name to any primitive (int, float,char), derived (array, string) , and as well as user defined datatype (structure, union).
• We can use typedef either globally and locally.

Syntax: typedef dataType name;
Declaration: typedef int myint;

Example of typedef in primitive data type:-

Example of typedef in derived dataType:-

Example of typedef in User defied dataType:-

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15. Storage Classes in C

Every Variable in C Programming has two properties one is dataType and second is Storage class.

We all know that dataType is a representation of data like how much memory is required, which type of data is allowed, etc. Now one more question is arrise:-

Q. What represents Storage class about Variable?

storage class represent many things that is:-

• Where variable gets memory allocation.
• What is the default value of a variable.
• What is the scope of a variable like block scope, method or function scope, program scope.
• What is the lifetime of a variable

Types of scope:-

1. Block scope:-

when we declare a variable inside of any particular block then  we cannot access that variable out of that block is called block scope of that variable.

2. Method or Function scope:-

when we declare a variable inside of any particular function then we cannot access that variable in another function is called function scope of that variable.

when we declare any Global variable then it can be access in any function of that program. It is called the Program scope of a variable.

Every program processing is always taken place in register memory of CPU which is the fastest memory of computer. Whenever we declare any auto variable then it will allocate memory inside the RAM but RAM is not process data for this work it call to register memory inside the CPU. It should be noted that memory allocation of a program inside the RAM but 4 process RAM call to register means RAM giving one by one instruction to register and this process is time consuming. 

2. By double click

Prototype: int atoi(char* str);

2. atof();

stands for “automatic float”. Used to convert string into float.
Prototype: int atof(char* str);

Example: atof(23.45);