RENAME()

this function is used to rename a file or directory in the filesystem.

int rename(const char *old_filename, const char *new_filename);

 * old_filename: The current name/path of the file or directory
 * new_filename: The new name/path you want to assign
 * Return value:
    - 0 on success
    - Non-zero (usually -1) on failure (errno is set)
    
 * Changes the name of a file or directory from old_filename to new_filename
 * Can also move the file to a different directory (if on the same filesystem)
 * Overwrites new_filename only on POSIX systems if the file 
   exists (not allowed by default on Windows)

 * Error examples:
    - ENOENT — old_filename does not exist
    - EACCES — Permission denied
    - EXDEV — Moving across filesystems is not allowed
    
 * POSIX
    - Overwrites new_filename if it exists (if permitted)
   Windows
    - Fails if new_filename already exists

#include <stdio.h>

int main() {
    if (rename("oldname.txt", "newname.txt") == 0) {
        printf("File renamed successfully.\n");
    } else {
        perror("Error renaming file");
    }
    return 0;
}