c - Unexpected behaviour, Garbage prints after string -

i trying animate strings before terminating application. called attached piece of code so. keeps on printing garbage till core dumped.

here code..

int terminate_msg(int quit_flag) {     char server_msg[] = "\napplication not alive";     char exit_msg[] = "\nterminating application...\n";     char *ch;     int = 0;      if(quit_flag == 1) {         printf("%s%s", server_msg, exit_msg);         while((ch = server_msg + i) != null) {             printf("%c",*ch);             fflush(stdout);             usleep(100000);             i++;         }         = 0;         sleep(2);         while((ch = exit_msg + i) != null) {             printf("%c",*ch);             fflush(stdout);             usleep(100000);             i++;         }         sleep(2);     }        return 0; } 

output:

application not alive terminating application...  application not alive terminating application... ���І�js�dx��lx���p�dx��x��$���p l�uz��d~�]p�up��is�@q�p�q�m�dx��І@��!p�\x��^c 

though first printf() prints correctly, don't know why garbage prints coming @ end. if there problem, garbage should come after first while loop also.

note that, when comparing *ch != '\0', working fine.

what wrong piece of code? i'm using gcc in linux environment.

this condition wrong

while((ch = server_msg + i) != null) 

you should try this

char ch;  while ((ch = server_msg[i]) != '\0')     printf("%c", ch); 

the condition testing if pointer null, isn't going happen, must test if '\0' terminating byte reached, need dereference pointer.

since null (void *) 0 in c, , if server_msg valid pointer it's value > 0, value of (void *) 0 unreachable incrementing pointer, loop never ends , program continues access pointer after it's passed valid memory points to.

of course, same problem happens here

while((ch = exit_msg + i) != null) {