Case and Switch Statements
Switch statements (in some languages, case statements or multiway branches) compare a given value with specified constants and take action according to the first constant to match. There is usually a provision for a default action ('else','otherwise') to be taken if no match succeeds. Switch statements can allow compiler optimizations, such as lookup tables. In dynamic languages, the cases may not be limited to constant expressions, and might extend to pattern matching, as in the shell script example on the right, where the '*)' implements the default case as a regular expression matching any string.
| Pascal: | C: | Java: | Shell script: |
|---|---|---|---|
| case someChar of 'a': actionOnA; 'x': actionOnX; 'y','z':actionOnYandZ; else actionOnNoMatch; end; | switch (someChar) { case 'a': actionOnA; break; case 'x': actionOnX; break; case 'y': case 'z': actionOnYandZ; break; default: actionOnNoMatch; } | switch (age) { case 1: System.out.printf("You're one."); break; case 2: System.out.printf("You're two."); break; case 3: System.out.printf("You're three."); break; case 4: System.out.printf("You're four."); break; default: System.out.printf("You're neither!"); break; } | case $someChar in a) actionOnA; ;; x) actionOnX; ;; ) actionOnYandZ; ;; *) actionOnNoMatch ;; esac |
Read more about this topic: Conditional (computer Programming)
Famous quotes containing the words case, switch and/or statements:
“My case is thrown exclusively upon the independent voters of this county, and if elected they will have conferred a favor upon me, for which I shall be unremitting in my labors to compensate.”
—Abraham Lincoln (1809–1865)
“Uncritical semantics is the myth of a museum in which the exhibits are meanings and the words are labels. To switch languages is to change the labels.”
—Willard Van Orman Quine (b. 1908)
“We assume that politicians are without honor. We read their statements trying to crack the code. The scandals of their politics: not so much that men in high places lie, only that they do so with such indifference, so endlessly, still expecting to be believed. We are accustomed to the contempt inherent in the political lie.”
—Adrienne Rich (b. 1929)