string concatenation without using the library function in c?

Question

I am writing code to emulate the strcat function in the c library and I can't pass my first test in main. I was wondering if someone could guide me as to why. here is my code:

#include <stdio.h>

char *strcat(char string1[ ], char string2[ ])
{
    int i;
    int j;


    for(i = 0; string1[i] != '\0'; i++);

    for(j=0;string2[j] != '\0';j++)
    {

        string1[i] = string2[j];
        i++;


    }

    string1[i] = '\0';
}



int main() { 
    char str1[81], str2[81]; 
    char again = 'y', newline; 
    while (again == 'y') { 
        printf("Enter a string\n"); 
        scanf("%s", str1); 
        printf("Enter another string\n"); 
        scanf("%s", str2); 
        printf("The concatention is %s\n", strcat(str1, str2)); 
        printf("Second test:  The concatenation is %s\n", str1);
        printf("The second string is still %s\n", str2); 
        printf("Again? (y/n)\n"); 
        scanf("%c%c", &newline, &again); 
    }
}

Please take a look at the contract for strcpy() in C99 with Technical corrigenda TC1, TC2, and TC3 included. — Deduplicator
– Deduplicator, Commented Apr 12, 2014 at 16:04

BLUEPIXY · Accepted Answer · 2014-04-12 18:30:53Z

1

You must return the string1 is strcat.

return string1;

answered Apr 12, 2014 at 18:30

BLUEPIXY

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