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:
“The case of Andrews is really a very bad one, as appears by the record already before me. Yet before receiving this I had ordered his punishment commuted to imprisonment ... and had so telegraphed. I did this, not on any merit in the case, but because I am trying to evade the butchering business lately.”
—Abraham Lincoln (1809–1865)
“Children ... after a certain age do not welcome parental advice. Occasionally, they may listen to another adult, which is why perhaps people should switch children with their neighbors and friends for a while in the teen years!”
—Marian Wright Edelman (20th century)
“Is it true or false that Belfast is north of London? That the galaxy is the shape of a fried egg? That Beethoven was a drunkard? That Wellington won the battle of Waterloo? There are various degrees and dimensions of success in making statements: the statements fit the facts always more or less loosely, in different ways on different occasions for different intents and purposes.”
—J.L. (John Langshaw)