Question

How to add spaces to a number every 4 digits in C

Answer 1

#include <stdio.h>
#include <string.h>

void add_spaces_to_number_every_4_digits(char cardNumber[], char cardNumberWithSpaces[]) {
     for (int i = 0, j = 0; i < strlen(cardNumber); i++) {
        if (i > 0 && i % 4 == 0) {
            cardNumberWithSpaces[j++] = ' ';
        }
        cardNumberWithSpaces[j++] = cardNumber[i];
    }
    
    cardNumberWithSpaces[strlen(cardNumber) + (strlen(cardNumber) / 4)] = '\0';
}

int main() {
    char cardNumber[] = "9003125334656789";
    char cardNumberWithSpaces[32]; 

    add_spaces_to_number_every_4_digits(cardNumber, cardNumberWithSpaces);

    printf("%s\n", cardNumberWithSpaces);
    
    return 0;
}



/*
run:

9003 1253 3465 6789

*/

 

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