C

# Learn how to reverse a number in C language

In this article, you’ll learn how to reverse a number in C language without giving input from the keyboard or giving input from the keyboard.

In the above diagram, First, imagine the output screen

Enter a number:8614

if user write 4168 then our next step is to reverse the number that user enter and print on the screen in the next line;

Reverse number: 4168

To reverse the number we create three variable x, r and initially y=0. We store the entered number by the user in x variable, and take one number from right-hand side ( i.e.,8 in this program) and store in variable r, then from r store the number in variable y.

For doing the above process we follow the following step:

• x%10; it means 8614%10 gives remainder 4 and r=x%10; store the number 4 in variable r,
• y=r then from r variable the number 4 is stored in variable y which is initially 0. So y=4;
• x=x/10; it means 8614/10 then it gives the result i.e.,

#### again, repeat this process until x=0;

• now the new value of x=861
• x%10; it means 861%10 gives remainder 1 then store this number in variable r i.e.; r=x%10;
• when 2nd time store the value of r in variable y, then multiply 10 by the previous value of y and add the value of r i.e.; y=10*y+r; put the value of y and r we get the new value of y. y=10*4+1; so new value of y=41
• x/10; it gives a new value of x that is 86

#### Repeat the above process until x=0. Then we find the reverse number of x that is stored in variable y and print the variable y to get the result.

Example 1: write a program in C language to print a reverse of a number without giving input from keyboard

 #include #include int main() { int x=8614,y=0,r; while(x!=0){ r=x%10; y=y*10+r; x=x/10; } printf(“Reverse number = %d”,y); getch(); }

 The Output of this program: Reverse number = 4168

Example 2: write a program in C language to print reverse of a number, the input is given by the user from the keyboard.

Solution:

 #include #include int main() { int x,y=0,r; printf(“Enter a number: “); scanf(“%d”,&x); while(x!=0){ r=x%10; y=y*10+r; x=x/10; } printf(“Reverse number = %d”,y); getch(); }

 The Output of this program: Enter a number: 12345 Reverse number = 54321

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