why main(int argc, char** argv) allow to override argv parameters, why and how this work?

I found that main() allow override the argv[] parameters, as because they are not const.

#include <cstdio>

int main(int argc, char** argv)
{
    printf("%i %s\n",argc, argv[1]);
    argv[1][0] = 'X';
    argv[1][4] = 'X';
    printf("%i %s\n",argc, argv[1]);
    return 0;
}

and below is the result, it compiled and worked.

at first i expected some program crush like undefined behave however it may make sense that i may want to have a program that accept sensitive data as parameter but after i use it i would like to override it it immediately, is this is the only reason or there are others?

i would like to understand how this is work. i.e where are the char** argv[] strings array is located? how it created and deleted? etc.

>Solution :

On Linux/x86-64 the argc, argv, env is stored on the call stack by the kernel doing the execve(2) according to ABI conventions

See also this and the Linux Assembly HOWTO