Editing Conditional (computer programming) (section)

== Case and switch statements ==

{{Main|Switch statement}}

[[Switch statement]]s (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 [[Optimizing compiler|compiler optimizations]], such as [[lookup table]]s. 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.

{| class="wikitable"
|-
! [[Pascal (programming language)|Pascal]]:
! [[C (programming language)|C]]:
! [[Shell script]]:
|-
|<syntaxhighlight lang="pascal">
case someChar of
  'a': actionOnA;
  'x': actionOnX;
  'y','z':actionOnYandZ;
  else actionOnNoMatch;
end;
</syntaxhighlight>
|<syntaxhighlight lang="c">
switch (someChar) {
  case 'a': actionOnA; break;
  case 'x': actionOnX; break;
  case 'y':
  case 'z': actionOnYandZ; break;
  default: actionOnNoMatch;
}
</syntaxhighlight>
|<syntaxhighlight lang="bash">
case $someChar in 
   a)    actionOnA; ;;
   x)    actionOnX; ;;
   [yz]) actionOnYandZ; ;;
  *)     actionOnNoMatch  ;;
esac
</syntaxhighlight>
|}