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Comment by xigoi

5 months ago

The problem is when you accidentally write an infinite loop. In a different language, you run the code, see that it gets stuck and fix it. In C, the compiler may delete the function, making it hard to realize what is happening.

5 comments

xigoi

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account42  5 months ago

This is not a problem that C or C++ programmers actually encounter, ever.

  • ncruces  5 months ago

    I actually encountered it a couple weeks ago.

    Can you spot the infinite loop in this function?

      char* strcpy(char* restrict d, const char* restrict s) {
    stpcpy(d, s);
    return d;
  }

    I'll help. A call to `stpcpy` that ignores the return value can be swapped with a call to the (more likely to be optimized) `strcpy`. Since that's infinite recursion, and there is no forward progress, it's undefined behavior and anything goes.

    This isn't just theory, it actually broke things in practice for me.