对 main 的 argc argv有点困惑 写了实验代码

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

int
main( int argc, char** argv )
{
        int i = 0;
        for ( ; i < argc; i++ )
        {
                printf( "argv[%d] is %s\n", i, argv[i] );
        }

        int arg_c = argc;
        char** arg_v = argv;

        arg_c--, arg_v++;
        while (arg_c > 0 && *arg_v[0] == '-') {
                while (*++arg_v[0])
                {
                        switch (*arg_v[0])
                        {       
                                case 'v':
                                        printf("v\n");
                                        break;
                                case 'q':
                                        printf("q\n");
                                        break;
                                case 'f':
                                        printf("f\n");
                                        break;
                                default:
                                        break;
                        }
                //argc--, av++;
                }
                arg_c--, arg_v++;
        }

        for ( i = 0 ; i < argc; i++ )
        {
                printf( "argv[%d] is %s\n", i, argv[i] );
        }
        printf( "size of 4 is %d and null is %d\n", sizeof(argv[4]), sizeof('\0'));

        exit(0);
}