C program to reverse the digits of a number ? [ In 3 Steps ]

C program to reverse the digits of a number ? [ In 3 Steps ]

Problem Statement : Reversing the digits of number without using mod (%) Operator ?

Prerequisite :

• Atoi function
• Sprintf function

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<string.h>
void main()
{
 int num1, num2;
 char str[10];
 clrscr();
    printf("\nEnte the Number : ");
    scanf("%d",&num1);
    sprintf(str,"%d",num1);
    strrev(str);
    num2 = atoi(str);
    printf("\nReversed Number : ");
    printf("%d\n",num2);
    getch();
}

Output :

Enter the Number : 123
Reversed Number : 321

Explain Logic :
Step 1 : Store Number in the Form of String

• Sprintf function sends formatted output to string variable specified
• Number will be stored in String variable “str”

sprintf(str,"%d",num1);

Step 2 : Reverse the String Using Strrev Function

• Strrev will reverse String
• eg “1234″ will be reversed as “4321″

strrev(str);

Step 3 : Convert String to Number

• [A to I ] = [ Alphabet to Integer ] = atoi
• Atoi function Converts String to Integer

num2 = atoi(str);

Incoming search terms:

• c program to reverse a number witout using mode (2)
• atoi for reverse string (1)
• logic reverse digits in c (1)
• logics to reverse 3 digit number in c language (1)
• number tricks in 3 steps (1)
• reverse a number in c logic (1)