Where do gaps come from?

Question

C++ / C#

The program must remove spaces at the beginning and at the end of the string. In a function, it does its job, but when it returns to main, it breaks.

#include <stdio.h>
#include <stdlib.h>

int size(const char str[])
{
    int i = 0;
    while(str[i] != '\0')
    {
        i++;
    }
    return i;
}

void mutableStrip(char str[])
{
    int start = 0;
    while(str[start] == ' ')
    {
        start++;
    }

    int n = size(str);
    int end = 0;
    while(str[(n-1) - end] == ' ')
    {
        end++;
    }

    str[n-end] = '\0';
    str += start;

    printf("0%s1 \n", str);
}

int main()
{
    char str[] = "  ads  fh ";

    mutableStrip(str);
    printf("0%s1 \n", str);
    return 0;
}

conclusion:

0ads  fh1
0  ads  fh1

Added 0 and 1 to show where the line starts and ends.

For some reason, spaces appear in the main, although there are none in the function.

Answer 1

Great, the answer was deleted...
So, once again: str is a pointer, it is passed to the function by value, you cannot change it, this does not affect str after returning from the function:
str += start;