c - Find the fault or error -

can find wrong following code?

int main(){     char *p="hai friends",*p1;     p1=p;     while(*p!='\0') ++*p++;     printf("%s %s",p,p1); } 

i expected print space followed string!

here way use ++*p++:

#include <stdio.h> #include <string.h>  int main(int argc, char* argv[]) {   char *p = "my test string", p1[15];    strncpy(p1, p, 14);   p1[14] = 0;   p = p1;    while (*p != 0) {     printf("%c", ++*p++);   } } 

note p1 array of memory (usually) allocated on stack, whereas p (usually) pointer read memory, above code moves point p1 instead of (usually) read location string resides. operating systems and/or compilers exhibit other behavior, 1 of protection mechanisms built modern oss prevent classes of viruses.