MATLAB Function Reference

switch

Switch among several cases based on expression

Syntax

• switch switch_expr
    case case_expr 
      statement,...,statement
    case {case_expr1,case_expr2,case_expr3,...}
      statement,...,statement
  ...
    otherwise
      statement,...,statement
  end
  

Discussion

The switch statement syntax is a means of conditionally executing code. In particular, switch executes one set of statements selected from an arbitrary number of alternatives. Each alternative is called a case, and consists of:

• The case statement
• One or more case expressions
• One or more statements

In its basic syntax, switch executes the statements associated with the first case where switch_expr == case_expr. When the case expression is a cell array (as in the second case above), the case_expr matches if any of the elements of the cell array match the switch expression. If no case expression matches the switch expression, then control passes to the otherwise case (if it exists). After the case is executed, program execution resumes with the statement after the end.

The switch_expr can be a scalar or a string. A scalar switch_expr matches a case_expr if switch_expr==case_expr. A string switch_expr matches a case_expr if strcmp(switch_expr,case_expr) returns 1 (true).

Note for C Programmers    Unlike the C language switch construct, the MATLAB switch does not "fall through." That is, switch executes only the first matching case, subsequent matching cases do not execute. Therefore, break statements are not used.

Examples

To execute a certain block of code based on what the string, method, is set to,

• method = 'Bilinear';
  
  switch lower(method)
     case {'linear','bilinear'}
        disp('Method is linear')
     case 'cubic'
        disp('Method is cubic')
     case 'nearest'
        disp('Method is nearest')
     otherwise
        disp('Unknown method.')
  end
  
  Method is linear
  

See Also

case, end, if, otherwise, while

svds

symamd