Thread: a function which takes a character array and reverses it

this was a question from my first exam and it says

write a c function which takes a string(as a character array, null terminated) and reverses it. it doesn't print the reversed string -- it modifies the given string so that it is reversed.

Code:

void reverse(char array[])
{
        char tmp;
        int i, j;
        for(i=0;i<strlen(array); i++)
        {
                for(j=strlen(array)-1;j>=0;j--)
                {
                        tmp = array[i];
                        array[i] = array[j];
                        array[j] = tmp;
                }
        }
}

how come this doesn't work?