Question

How to check if a number contains identical digits in C

Answer 1

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
   
char* set(char str[]) {
    int index = 0;
   
     for (int i = 0; str[i] != '\0'; i++) {
        int j;
        for (j = 0; j < i; j++) {
            if (str[i] == str[j]) {
                break;
            }
        }
    
        if (j == i) {
            str[index++] = str[i];
        }
    }
    
    str[index] = '\0';
    
    return str;
}
   
bool isNumberContainIdenticalDigits(int num) {
    char str[16];
 
    sprintf(str, "%d", num);
    
    return strlen(set(str)) == 1;
}
   
int main() {
    int num = 7777777;
       
    if (isNumberContainIdenticalDigits(num)) {
        puts("yes");
    } else {
        puts("no");
    }
       
    return 0;
}
   
   
   
/*
run:
   
yes
   
*/

 

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