程序代码：

#include "stdio.h"
#include "stdlib.h"
#include "windows.h"

int main(void)
{
    char *str = "kankan";
   
    DWORD new_p = 0x40;
    DWORD old_p;
       
    printf ("%s\n", str);

    VirtualProtect (str, 6, new_p, &old_p);
        str[2] = 'k';       
        //"kankan"[2] = 'k';        这样也可以
    VirtualProtect (str, 6, old_p, &new_p);
   
    printf ("%s\n", str);

    system ("pause");
    return 0;
}