Passing a pointer to char array, and getting that arrays length in C?

Question

How can I get the length of the array 'source'? I have this so far I was wondering if anyone had any suggestions. Thank you

For size I get -2074.

I do not know the length of the array, it's a random input.

#include <ctype.h>

int StrToUpper(char *destination[],  const char *source[])
{
    int size = *(&source + 1) - source;

    return size;
}

You can't get the size of an "array" if all you have is a pointer. The program just doesn't have any information about what a pointer might point to. — Some programmer dude, Jan 16 '21 at 07:31
This is a copy of OP's (now deleted) [same question](https://stackoverflow.com/questions/65746396/how-to-get-the-length-of-an-array-sent-to-a-function-without-knowing-its-length), which was closed as a duplicate a few hours ago. — dxiv, Jan 16 '21 at 07:34
yah, sorry, my other was answered, and I tried to post it but it wouldn't let me. — Nemo, Jan 16 '21 at 07:37
Note that `char *source[]` doesn't declare `source` as a pointer to an array, it's an array of pointers (or really a pointer to a pointer or `char **source`). If you want a pointer to an array you need to use `char (*source)[]`. Which in this case doesn't make any difference. — Some programmer dude, Jan 16 '21 at 07:37
That link helps, but I'm still really lost, because its a hw problem and we don't know what string he is gonna input — Nemo, Jan 16 '21 at 07:38
Do you really need the *size* of the arrays? Or the *string length*? What is the use-case? What is the actual underlying problem you need to solve? — Some programmer dude, Jan 16 '21 at 07:40

score 1 · Accepted Answer · edited Jan 16 '21 at 08:00

1

You can do something like:

int StrToUpper(char *destination[],  const char *source)
{
    int size = 0;
   
    while(source[size] != '\0')
        size++;

    return size;
}

I am assuming that you will be passing string to this function like: StrToUpper("some","somemore")

edited Jan 16 '21 at 08:00

David Ranieri

answered Jan 16 '21 at 07:51

chaitanya

1 Answers1