Question

I’ve searched, but all I can find is where a function to reverse a string in place. Here’s what I have so far:

char* reverseString(char* string)
{
    int i, j;
    char reversed[sizeof(string)];
    j = strlen(string);

    for (i = strlen(string); i >= 0; i--)
    {
        reversed[j - i] = string[i];
    }
    return reversed;
}

However, that hits the issue of reversed being a local variable, so returning a pointer to it throws

warning: function returns address of local variable [enabled by default]

Answer 1

You can dynamically allocate memory for it:

char* reverseString(char* string)
{
    int i;
    int j = strlen(string);
    char *reversed = malloc(j + 1);
    ...

In this case, the caller must remember to free() the allocated buffer that is returned.

Or you can have caller to pass in a buffer that’s large enough to hold the reversed string:

char* reverseString(char* string, char *reversed)
{
     int i, j;
     j = strlen(string);

     for (i = strlen(string); i >= 0; i--)
     {
 ...

Note also that in your current code: char reversed[sizeof(string)]; is wrong,
inside this function string is just a char* , so sizeof(string) gives you the size of a char*, not the length of the string this char* points to.