Wisdom a ray hope.: C Programming tutorials

What is C Language?

C is a programming language. The C language was developed by Dennis Ritchie in 1972 at AT&T Bell Labs. It was called his newly developed language C simply because there was a B programming language already and the B language led to the development of C Language. C language is based on ALGOL and B languages.

As said above C language is a programming language. Programming language is any language that computer system can understand directly or indirectly to can perform the actions asked by the programmer as set of instructions in form of a computer program.

C language is a high-level programming language. In the computer world, the further a programming language is from the computer architecture, the higher the language's level. You can imagine that the lowest-level languages are machine languages that computers understand directly. The high-level programming languages, on the other hand, are closer to our human languages.

A computer program written in a high-level language, such as C, Java, or Perl, is just a text file, consisting of English-like characters and words. We have to use some special programs, called compilers or interpreters, to translate such a program into a machine-readable code. That is, the text format of all instructions written in a high-level language has to be converted into the binary format. The code obtained after the translation is called binary code. Prior to the translation, a program in text format is called source code. The smallest unit of the binary code is called a bit (from binary digit), which can have a value of 0 or 1. 8 bits make up one byte, and half a byte (4 bits) is one nibble.

C programming codes

c program examples

Example 1 - C hello world program
/* A very simple c program printing a string on screen*/

#include <stdio.h>
 
main()
{
    printf("Hello World\n");
    return 0;
}

Output of above program:
"Hello World"

Example 2 - c program to take input from user using scanf

#include <stdio.h>
 
main()
{
   int number;
 
   printf("Enter an integer\n");
   scanf("%d",&number);
 
   printf("Integer entered by you is %d\n", number);
 
   return 0;
}

Output:
Enter a number
5
Number entered by you is 5

Example 3 - using if else control instructions

#include <stdio.h>
 
main()
{
   int x = 1;
 
   if ( x == 1 )
      printf("x is equal to one.\n");
   else
      printf("For comparison use == as = is the assignment operator.\n");
 
   return 0;
}

Output:
x is equal to one.

Example 4 - loop example

#include <stdio.h>
 
main()
{
   int value = 1;
 
   while(value<=3)
   {
      printf("Value is %d\n", value);
      value++;
   }
 
   return 0;
}

Output:
Value is 1
Value is 2
Value is 3

Example 5 - c program for prime number

#include <stdio.h>
 
main()
{
   int n, c;
 
   printf("Enter a number\n");
   scanf("%d", &n);
 
   if ( n == 2 )
      printf("Prime number.\n");
   else
   {
       for ( c = 2 ; c <= n - 1 ; c++ )
       {
           if ( n % c == 0 )
              break;
       }
       if ( c != n )
          printf("Not prime.\n");
       else
          printf("Prime number.\n");
   }
   return 0;
}

Example 6 - command line arguments

#include <stdio.h>
 
main(int argc, char *argv[])
{
   int c;
 
   printf("Number of command line arguments passed: %d\n", argc);
 
   for ( c = 0 ; c < argc ; c++)
      printf("%d. Command line argument passed is %s\n", c+1, argv[c]);
 
   return 0;
}

Above c program prints the number and all arguments which are passed to it.

Example 7 - Array program

#include <stdio.h>
 
main() 
{
    int array[100], n, c;
 
    printf("Enter the number of elements in array\n");
    scanf("%d", &n);
 
    printf("Enter %d elements\n", n);
 
    for ( c = 0 ; c < n ; c++ ) 
        scanf("%d", &array[c]);
 
    printf("Array elements entered by you are:\n");
 
    for ( c = 0 ; c < n ; c++ ) 
        printf("array[%d] = %d\n", c, array[c]);
 
    return 0;
}

Example 8 - function program

#include <stdio.h>
 
void my_function();
 
main()
{
   printf("Main function.\n");
 
   my_function();
 
   printf("Back in function main.\n");
 
   return 0;
}
 
void my_function()
{
   printf("Welcome to my function. Feel at home.\n");
}

Example 9 - Using comments in a program

#include <stdio.h>
 
main()
{
   // Single line comment in c source code
 
   printf("Writing comments is very useful.\n");
 
   /*
    * Multi line comment syntax
    * Comments help us to understand code later easily.
    * Will you write comments while developing programs ?
    */
 
   printf("Good luck c programmer.\n"); 
 
   return 0;
}

Example 10 - using structures in c programming

#include <stdio.h>
 
struct programming
{
    float constant;
    char *pointer;
};
 
main()
{
   struct programming variable;
   char string[] = "Programming in Software Development.";   
 
   variable.constant = 1.23;
   variable.pointer = string;
 
   printf("%f\n", variable.constant);
   printf("%s\n", variable.pointer);
 
   return 0;
}

Example 11 - c program for Fibonacci series

#include <stdio.h>
 
main()
{
   int n, first = 0, second = 1, next, c;
 
   printf("Enter the number of terms\n");
   scanf("%d",&n);
 
   printf("First %d terms of Fibonacci series are :-\n",n);
 
   for ( c = 0 ; c < n ; c++ )
   {
      if ( c <= 1 )
         next = c;
      else
      {
         next = first + second;
         first = second;
         second = next;
      }
      printf("%d\n",next);
   }
 
   return 0;
}

Example 12 - c graphics programming

#include <graphics.h>
#include <conio.h>
 
main()
{
    int gd = DETECT, gm;
 
    initgraph(&gd, &gm,"C:\\TC\\BGI");
 
    outtextxy(10,20, "Graphics source code example.");
 
    circle(200, 200, 50);
 
    setcolor(BLUE);
 
    line(350, 250, 450, 50);
 
    getch();
    closegraph( );
    return 0;
}

For GCC users

If you are using GCC on Linux operating system then you need to modify programs. For example consider the following program which prints first ten natural numbers

#include <stdio.h>
#include <conio.h>
 
int main()
{
    int c;
 
    for ( c = 1 ; c <= 10 ; c++ )
        printf("%d\n", c);
 
    getch();
    return 0;
}

Above source code includes a header file <conio.h> and uses function getch, but this file is Borland specific so it works in turbo c compiler but not in GCC. So the code for GCC should be like

#include <stdio.h>
 
int main()
{
    int c;
 
    /* for loop */
 
    for ( c = 1 ; c <= 10 ; c++ )
        printf("%d\n", c);
 
    return 0;
}

If using GCC then save the code in a file say numbers.c, to compile the program open the terminal and enter command GCC numbers.c, this will compile the program and to execute the program enter command ./a.out .

Frequently asked c programs in interview

1. Write a c program to check given number is perfect number or not.

2. Write a c program to check given number is Armstrong number or not.

3. Write a c program to check given number is prime number or not.

4. Write a c program to check given number is strong number or not.

5. C program to check a number is odd or even.

6. Write a c program to check given number is palindrome number or not.

8. Write a c program to check given string is palindrome number or not.
7. Write a c program to solve quadratic equation.
8. Write a c program to print Fibonacci series of given range.
9. Write a c program to get factorial of given number.

10. Write a c program for Floyd’s triangle.

11. Write a c program to print Pascal triangle.

12. Write a c program to generate multiplication table.
13. Write a c program to print ASCII value of all characters.
14. C program to print hello world without using semicolon
15. Write a c program which produces its own source code as its output

C program with numbers

1. Write a c program to reverse any number.
2. Write a c program to find out sum of digit of given number.

3. Write a c program to find out power of number.

4. Write a c program to add two numbers without using addition operator.

5. Write a c program to subtract two numbers without using subtraction operator.

6. Write a c program to find largest among three numbers using binary minus operator.

7. Write a c program to find largest among three numbers using conditional operator

8. Write a c program to find out generic root of any number.

9. Write a c program to find out prime factor of given number.

10. Write a c program to find out NCR factor of given number.
11. How to convert string to int without using library functions in c
12. Program in c to print 1 to 100 without using loop
13. C program for swapping of two numbers
14. Program to find largest of n numbers in c
15. Split number into digits in c programming
16. C program to count number of digits in a number

Recursion
Example of recursion in c programming

L.C.M and H.C.F.

1. Write a c program to find out L.C.M. of two numbers.

2. Write a c program to find out H.C.F. of two numbers.

3. Write a c program to find out G.C.D. of two numbers.

Swapping

1. Write a c program to swap two numbers.

2. Write a c program to swap two numbers without using third variable.

3. Write a c program for swapping of two arrays.

4. Write a c program for swapping of two string.

Conversion ( Number System )

1. Write a c program to convert decimal number to binary number.

2. Write a c program to convert decimal number to octal number.
3. Write a c program to convert decimal number to hexadecimal number.
4. Write a c program to convert octal number to binary number.

5. Write a c program to convert octal number to decimal number.

6. Write a c program to convert octal number to hexadecimal number.

7. Write a c program to convert hexadecimal number to binary number.

8. Write a c program to convert hexadecimal number to octal number.
9. Write a c program to convert hexadecimal number to decimal number.
10. Write a c program to convert binary number to octal number.

11. Write a c program to convert binary number to decimal number.

12. Write a c program to convert binary number to hexadecimal number.
13. C program for addition of binary numbers .
14. C program for multiplication of two binary numbers.
15. C program fractional binary conversion from decimal.
16. C program for fractional decimal to binary fraction conversion.
17. C program to convert decimal number to roman.
18. C program to convert roman number to decimal number.
19. C program to convert each digits of a number in words
20. C program to convert currency or number in word.

Conversion ( Unit )

1. C program for unit conversion.

String

1. Write a c program to convert the string from upper case to lower case.

2. Write a c program to convert the string from lower case to upper case.

3. Write a c program to delete the all consonants from given string.

4. Write a c program to count the different types of characters in given string.

5. Write a c program to sort the characters of a string.

6. Write a c program for concatenation two strings without using string.h header file.

7. Write a c program to find the length of a string using pointer.

8. Write a c program which prints initial of any name.

9. Write a c program to print the string from given character.
10. Write a c program to reverse a string
11. Reverse a string using recursion in c
12. String concatenation in c without using strcat
13. How to compare two strings in c without using strcmp
14. String copy without using strcpy in c
15. Convert a string to ASCII in c

Matrix

1. Write a c program for addition of two matrices.

2. Write a c program for subtraction of two matrices

3. Write a c program for multiplication of two matrices.

4. Write a c program to find out sum of diagonal element of a matrix.

5. Write a c program to find out transport of a matrix.
6. Write a c program for scalar multiplication of matrix.
7. C program to find inverse of a matrix
8. Lower triangular matrix in c
9. Upper triangular matrix in c
10. Strassen's matrix multiplication program in c
11. C program to find determinant of a matrix

File

1. Write a c program to open a file and write some text and close its.

2. Write a c program to delete a file.

3. Write a c program to copy a file from one location to other location.

4. Write a c program to copy a data of file to other file.

5. Write a c program which display source code as a output.

6. Write a c program which writes string in the file.

7. Write a c program which reads string from file.

8. Write a c program which writes array in the file.

9. Write a c program which concatenate two file and write it third file.
10. Write a c program to find out size of any file.
11. Write a c program to know type of file.
12. Write a c program to know permission of any file.
13. Write a c program to know last date of modification of any file.
14. Write a c program to find size and drive of any file.

Complex number

1. Complex numbers program in c

2. Write a c program for addition and subtraction of two complex numbers.

3. Write a c program for multiplication of two complex numbers.

4. Write a c program for division two complex numbers.

Series

1. Write a c program to find out the sum of series 1 + 2 + …. + n.

2. Write a c program to find out the sum of series 1^2 + 2^2 + …. + n^2.

3. Write a c program to find out the sum of series 1^3 + 2^3 + …. + n^3.

4. Write a c program to find out the sum of given A.P.

5. Write a c program to find out the sum of given G.P.

6. Write a c program to find out the sum of given H.P.

7. Write a c program to find out the sum of series 1 + 2 + 4 + 8 … to infinity.

Array

1. Write a c program to find out largest element of an array.

2. Write a c program to find out second largest element of an unsorted array.

3. Write a c program to find out second smallest element of an unsorted array.

4. Write a c program which deletes the duplicate element of an array.

5. Write a c program for delete an element at desired position in an array.

6. Write a c program for insert an element at desired position in an array.
7. C program to find largest and smallest number in an array

Sorting

1. Write a c program for bubble sort.

2. Write a c program for insertion sort.

3. Write a c program for selection sort.

4. Write a c program for quick sort.

5. Write a c program for heap sort.

6. Write a c program for merge sort.

7. Write a c program for shell sort.

Recursion

1. Write a c program to find factorial of a number using recursion.

2. Write a c program to find GCD of a two numbers using recursion.

3. Write a c program to find out sum digits of a number using recursion.

4. Write a c program to find power of a number using function recursion.

5. Write a c program to reverse any number using recursion.

Size of data type

1. Write a c program to find the size of int without using sizeof operator.

2. Write a c program to find the size of double without using sizeof operator.

3. Write a c program to find the size of structure without using sizeof operator.

4. Write a c program to find the size of union without using sizeof operator.

Using pointer

1. Write a c program for concatenation two string using pointer.

Searching

1. Write a c program for linear search.

2. Write a c program for binary search.

3. Write a c program for binary search using recursion.

Area and volume

1. Write a c program to find the area of circle.

2. Write a c program to find the area of any triangle.
3. Write a c program to find the area of equilateral triangle.
4. Write a c program to find the area of right angled triangle.

5. Write a c program to find the area of rectangle.

6. Write a c program to find the area of trapezium.
7. Write a c program to find the area of rhombus.
8. Write a c program to find the area of parallelogram.

9. Write a c program to find the volume and surface area of cube.
10. Write a c program to find the volume and surface area of cuboids.
11. Write a c program to find the volume and surface area of cylinder.

12. Write a c program to find the surface area and volume of a cone.
13. Write a c program to find the volume and surface area of sphere.