Question

I was recently on The Daily WTF when I came across this old post. In it the author mentions that one of the programmers changed this code:

int main (int argc, char **argv) 
{ 
  int x;
  char data_string[15];
  ...
  x = 2;
  strcpy(data_string,"data data data");
  ...
}

To this code:

int main (int argc, char **argv) 
{
  int x = 2;
  char data_string[15] = "data data data";
  ...
}

The author goes on to mention:

[the coder] changed every single variable to be initiated on the stack

For the life of me I cannot see how this change could be harmful, and I am worried that it is a lapse in my C knowledge. What is the WTF?

Answer 1

I don’t think the stack initialization was the problem. He was supposed to be looking for a hard-to-find memory leak, but he decided to do the initialization change instead on thousands of C files.

Although, as mentioned on wikipedia, “uninitialized variables [are] a frequent cause of bugs”. You eliminate the potential for use of uninitialized variables if you take care of it at declaration. But doing that conversion to a few thousand files probably wasn’t the most efficient way to find and solve the real problem.