Why does this code work? There isn't enough space in the array to store the 6-char string (including the null-character) yet the program works.Code:#include <stdio.h> #include <stdlib.h> int main() { char str[1]; fgets(str, 100, stdin); //inputs hello printf("%s", str); //outputs hello return 0; }
Just because a program compiles doesn't mean it is correct. You happen to be invoking Undefined Behaviour, which means anything can happen including the program appearing to run properly.
Don't confuse 'works' with 'bug-free'.
Because the stack needs to be kept aligned, the compiler is likely to round up small arrays to some multiple of 2,4,8,16 bytes.
Your 6-byte string it would seem is just comfortably sitting in otherwise dead space.
The same code with another compiler on another machine, with the same input could just as easily crash as 'work'.
There is nothing in the standard that says a program should throw an exception every time you invoke undefined behaviour.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
