C Program to Reverse the digits of a number in 3 Steps

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

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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("%dn",num2);
    getch();
}

Output :

Enter the Number : 123
Reversed Number : 321

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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);