Conditional (computer programming)

Conditionals allow blocks of code to give different results based on true or false. The data type that allows for true or false is called a boolean.

The if statement is the most basic kind of conditional. It checks that a condition is true, then does an action based on a block of code.

if (condition) { } // code for if the condition is true 

By adding an else statement, it will be done, if the condition is false.

if (condition) { } // code for if the condition is true else { } // code if the condition is false 

By adding the else if statement, it is possible to check several conditions in a row, and do actions when the condition it checks for is true.

if (condition) { } // code for if this condition is true else if (condition) { } // code for if this condition is true else if (condition) { } // code for if this condition is true else { } // code for if none of the above conditions happen (false) 

A ternary operator is a special operator that is easier to type out and represents conditional statements in several programming languages.

? equals if and : equals else. Instead of if A then B else C, it would be A ? B : C.

int var = (condition) ? X : Y; 

Some languages do not use the ternary operator, but do similar, by typing out the if and else statement on the same line.

int var = if (condition) X else Y 

Switch statement is the most common term, but it might be called case or match, depending on the language. The switch statement can be used to replace if-else if-else statements.

case someChar of   'a': actionA;   'x': actionX;   'y','z':actionYandZ;   else actionNoMatch; end; 

switch (someChar) {   case 'a': actionA; break;   case 'x': actionX; break;   case 'y':   case 'z': actionYandZ; break;   default: actionNoMatch; } 

match some_char {   'a' {action_a}   'x' {action_x}   'y','z' {action_y_z}   else {action_no_match} }