Problem with realloc in the following function

I'm trying to write a function that doubles the size of an array of strings. The function also initializes all the new elements in the array to 100 char strings. However, the function doesnt work at all. I was wondering if someone could tell me what is wrong with it. Thanks.

Code:

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char **doubleStringArray(char **stringArray, int* size){

        int i;
        stringArray = (char**) realloc(stringArray, 2*(*size));
        for (i = (*size); i < 2*(*size); i++){
                stringArray[i] = (char*) malloc(100);
        }
        *size = 2 * (*size);

        return stringArray;

}

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There is nothing functionally wrong with it. You are probably using it wrong.

gg

> stringArray = (char**) realloc(stringArray, 2*(*size));
1. lose the casts - there is no need to cast memory allocation functions in C. At worst, it results in incorrect code because you hide your failure to include stdlib.h, and hence prototype the function properly.

2. the size of 2 is a big assumption about the size of pointers
It should be
sizeof(char*) * (*size )

3. If realloc fails, you lose your old allocation as well
Do it like so

Code:

---

char **t = realloc ( stringArray, sizeof(char*) * (*size) );
if ( t != NULL ) {
    stringArray = t;
} else {
    // realloc failed, but stringArray is still usable
}

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Quote:

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There is nothing functionally wrong with it.

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And by that I meant it compiles......yeah, that's the ticket.

gg

I multiply by 2 because I am doubling the size of the array, thats why I do that

And it still doesnt work after doing all that you said

> I multiply by 2 because I am doubling the size of the array
Then it's
2 * (*size) * sizeof(char*)

red is how many you want
blue is how big each one is