Computer Dictionary of Information Technology

switch statement

(Or case statement, multi-way branch) A construct found in most high-level languages for selecting one of several possible blocks of code or branch destinations depending on the value of an expression. An example in C is

	switch (foo(x, y))
	{
	case 1:  printf("Hello\n");	/* fall through */
	case 2:  printf("Goodbye\n"); break;
	case 3:  printf("Fish\n"); break;
	default: fprintf(stderr, "Odd foo value\n"); exit(1);
	}

The break statements cause execution to continue after the whole switch statemetnt. The lack of a break statement after the first case means that execution will fall through into the second case. Since this is a common programming error you should add a comment if it is intentional.

If none of the explicit cases matches the expression value then the (optional) default case is taken.

A similar construct in some functional languages returns the value of one of several expressions selected according to the value of the first expression. A distant relation to the modern switch statement is Fortran's computed goto.