Thread: About NULL pointer

Hi guys, just flagged in my head something like this, if I have started a pointer to string and write like this statement:

Code:

 char *p1 = strstr(ac_auto, "Cboard ") + 5

assuming strstr is defined and all things are alright(ac_auto is a string), but lets assume that's strstr is returning pointer "NULL" so NULL+5 isn't defined because NULL is void and can't be manipulated of. so what's happen in that case? I tried that in my PC the compilation is typically work but on the screen doesn't appear anything however I write printf after this case, meaning

Code:

 
char *p1 = strstr(ac_auto, "Cboard ") + 5 ;
printf("Hi");

but it doesn't print Hi if strstr returns NULL.

strstr() is a library function that returns the address of the substring. If the substring wasn't found the return value is NULL. you can't add an int-value to NULL. if you try, the program will crash.

besides: The address of the substring is not the index of that substring.

example:


char *ptr = strstr(phrase, "cool");
printf("%lu", ptr - phrase) // this prints out the index of the substring in the array
printf("%s", ptr); //this line prints the whole char array beginning with the found index