In this example, you will learn to reverse the given number using these two methods.
Examples :
Input : 123 Output : 321 Input : 1995 Output : 5991
Approach used :
We can reverse a number in c using loop and arithmetic operators.
- Take input number
- Find its quotient and remainder.
- Multiply the separate variable with 10 and add the obtained remainder to it.
- Do step 2 again for the quotient step 3 for the remainder obtained in step 4.
- Repeat the process until quotient becomes zero.
- When it becomes zero, print the output and exit.
Implementation :
1. Using while loop
// reverse a number using while loop #include<stdio.h> int main() { // take input int num = 123; int rem, reverse_num=0; // while loop while(num>=1) { // find reminder with num 10 // it finds last digit of number each time rem = num % 10; // this appending these reminders from LSB to MSB reverse_num = reverse_num * 10 + rem; // this truncate last digit of number num = num / 10; } // now, print reversed number of that number printf("Reverse of input number is: %d", reverse_num); // successful completion return 0; }
Output :
Reverse of input number is: 321
2. Using recursive program
// recursive program to reverse a number #include<stdio.h> // take initial reveresed number // and reminder variable int sum=0, rem; int reverse_function(int num){ if(num){ // find reminder with num 10 // it finds last digit of number each time rem=num%10; // this appending these reminders from LSB to MSB sum=sum*10+rem; // call this function again // after truncate last digit of number reverse_function(num/10); } else // else return return sum; // return return sum; } int main(){ // take input int num = 123; int reverse_number; // call user defined function to perform reverse reverse_number=reverse_function(num); // now, print reversed number of that number printf("Reverse of input number is: %d", reverse_number); // successful completion return 0; }
Output :
Reverse of input number is: 321
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