MISRA.SWITCH.WELL_FORMED.DEFAULT.FIRST_OR_LAST.2012

A default label shall appear as either the first or the last switch label of a switch statement.

MISRA C 2012 Rule 16.5: A default label shall appear as either the first or the last switch label of a switch statement

Category: Required

Analysis: Decidable, Single Translation Unit

Applies to: C90, C99

Rationale

This rule makes it easy to locate the default label within a switch statement.

Example

switch ( x ) 
{
  default:   /* Compliant - default is the first label                */ 
  case 0:
    ++x; 
    break; 
  case 1: 
  case 2:
    break; 
}

switch ( x ) 
{
  case 0:
    ++x; 
    break; 
  default:   /* Non-compliant - default is mixed with the case labels */
    x = 0; 
    break; 
  case 1: 
  case 2:
    break; 
}

switch ( x ) 
{
  case 0:
    ++x; 
    break; 
  case 1: 
  case 2:
    break; 
  default:   /* Compliant - default is the final label                 */
    x = 0; 
    break; 
}

See also

Rule 15.7, Rule 16.1