Question

How to check if a number is composed of a pair of duplicate digits next to each other in C

Answer 1

#include <stdio.h>
#include <math.h>
#include <stdbool.h>

bool hasDuplicateDigits(int n) {
    int total_digits = (int)floor(log10(n)) + 1;
    
    if (total_digits % 2 == 1) { // total digits not even
        return false;
    }
    
    while (n != 0) {
        int currentDigit = n % 10; 
        n /= 10; 
        int prevDigit = n % 10; 
        printf("%d : %d\n", prevDigit, currentDigit);
        if (currentDigit != prevDigit) {
            return false; 
        }
        n /= 10;
    }

    return true;
}

int main() {
    int number = 11338855; 

    if (hasDuplicateDigits(number)) {
        printf("yes");
    } else {
        printf("no");
    }

    return 0;
}

 
 
 
/*
run:
 
5 : 5
8 : 8
3 : 3
1 : 1
yes
 
*/

 

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