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Recursion

The program that swallowed its tail.

This chapter is about functions that call themselves. Consider the program below:

#include <stdio.h>

void black_hole()
{
  black_hole();
}

/* To shorten example, not using argp */
int main ()
{
  black_hole();
  return 0;
}

The main function calls the black_hole function, which calls itself, which calls itself, which calls... Once the control flow enters black_hole, it will never exit. This kind of function is called a recursive function, and a function's act of calling itself is called recursion.

• The stack:
• Controlled recursion:
• Controlled recursion with data structures:
• Recursion summary:
• Questions 21: