FAQ 32.02 What happens to a program that has even one wild pointer?

A wild pointer is to software what a car bomb is to a busy street: both cause indiscriminate pain and suffering.

After a program spawns its first wild pointer, an awesome chain reaction begins. The first wild pointer scribbles on a random memory location, which probably corrupts the object at that location, creating other wild pointers. Eventually almost mercifully one of these wild pointers attempts to scribble on something protected by the operating system or the hardware, and the program crashes.

By the time that happens, finding the root cause of the error with a debugger is nearly hopeless; what was once a cohesive system of objects is now a pile of rubble. The system has literally blown itself to bits.

Wild pointers create unstable systems. Arbitrarily small changes, such as inserting an extra semicolon, running the program on a different day of the week, or changing the way you smile as you press the Enter key can cause arbitrarily large changes in how the system behaves (or misbehaves). Sometimes the program deletes user files, sometimes it just gives the wrong answer, sometimes it actually works!

Wild pointers are a problem worth avoiding.