Thread: Is it possible to improve this program

I need my teacher today to pass the program, I wrote it and here's her code:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
int sizeRepeats(char *s, int count) //Get repeat str result size
{
    if(count <= 1)
        return -1;
    return (int)strlen(s)*count;
}

char * repeat(char *s, int count, char *dest)
{
    if(count <= 1)
        return "Error";
    for(int i=0; i<count; i++)
        strcat(dest, s);
    return dest;
}

int main(int argc, char const *argv[])
{
    char *str = "Testing";
    char buf[sizeRepeats(str, 5)];
    printf("'%s'\n", repeat(str, 5, buf));
    return 0;
}

Is this a normal release or can you do better and work even faster?

Code:

char * repeat(char *s, int count, char *dest)

Would better be

Code:

char * repeat(const char *s, int count, char *dest)

In addition to const qualifying 's', 'count' might be better as size_t. If you changed 'count' to size_t you may as well also get rid of the useless cast on line 9 and make that function return size_t as well. Line 23 should also be const qualified IMO since it would be undefined behaviour to modify what 'str' points to anyway.

What size is the array if sizeRepeats() returns -1?

I recommend you give a value to buf before the call to repeat().

Code:

strcpy(buf, str);