copy a fifth (20%) of an int array in c

Question

I was trying to copy the first 20% of an int array into another one but every time I tried, the VS debugger showed this error:

Unhandled exception at 0x00DB592A in Anti Virus.exe: 0xC0000005: Access violation reading location 0x00B41000.

here is the code:

/*
regularStr - the full arr
regularLen - its size
mode - what part of the array (first 20% or last)
quickFileLen - a pointer to where to put the shorten array size
*/
int* stringToQuickStr(int* regularStr, int regularLen, int mode, int* quickFileLen)
{
    int i = 0, start = 0;
    *quickFileLen = (regularLen / 5);
    int* quickStr = (int*)malloc(sizeof(int) * (*quickFileLen));
    if (!(quickStr))
    {
        printf("quickStr calloc() ERROR!\n");
        return -1;
    }
    if (mode == FIRST_20)
    {
        for (i = 0; i < *quickFileLen; i++)
        {
            quickStr[i] = regularStr[i];
        }
    }
    return quickStr;
    free(quickStr);
}

the program was always crashing in the FIRST_20 copy after some copying.

`i` is of type `int`, while `quickFileLen` is a pointer to `int`. Are you really comparing them in the for condition? — abhishek_naik, Jun 04 '16 at 13:34
Show the call to `stringToQuickStr()` and the variable definitions — pmg, Jun 04 '16 at 13:37
'free(quickStr);' ?? Will never be executed, which is not a bad thing actually:) — Martin James, Jun 04 '16 at 13:37
fileStrQUICK = stringToQuickStr(fileStr, &fileLen, FIRST_20, &quickFileLen); do you mean this? — Guy Shilman, Jun 04 '16 at 13:39
`&fileLen` is not compatible with `int`. Turn on your compiler warnings and **mind them**. — pmg, Jun 04 '16 at 13:41
Note that they say [you shouldn't cast the result of `malloc()` in C](http://stackoverflow.com/questions/605845/do-i-cast-the-result-of-malloc). — MikeCAT, Jun 04 '16 at 13:57
Use `fileLen` instead of `&fileLen` when you call the function. — Barmar, Jun 04 '16 at 13:59
You should return some other thing such as `NULL` on error because `-1` is not compatible with `int*` — MikeCAT, Jun 04 '16 at 14:00
@MikeCAT Yeah, this guy really doesn't grok the difference between pointers and integers. — Barmar, Jun 04 '16 at 14:06
@GuyShilman Please include the usage in your question by editing it. — MikeCAT, Jun 04 '16 at 14:07

copy a fifth (20%) of an int array in c

0 Answers0