recursion -- Definition

Recursion is  the technique  by which a  program or function  calls itself.
Because under  C, all  variables in a  function function have  local scope;
therefore, when a function calls  itself, it in effect recreates itself but
with a fresh copy of each of its variables.  The ``states'' of the previous
call  or calls  to  that function  are  stored on  the stack,  and are  not
modified when the function calls itself.

Recursion is a useful way to loop through a complex procedure.  Be careful,
however, that  you do not  lose track of  how the number of  times you have
called a given function; and be  careful not to pile the stack too high, or
you may have problems.

Example

The following program  demonstrates recursion.  In it, the function recur()
calls itself ten times.

#include <stdio.h>

main()
{
    printf("Before recursion ... \n");
    recur(1);
    printf("After recursion ... \n");
}

recur(level)
int level;
{
    printf("Entering call to recur() number %d\n", level);

    if (level < 10)
        recur(level+1);

    printf("Leaving call to recur() number %d\n", level);
}

See Also

programming COHERENT

© 2012 by Stephen A. Ness