MISRA.BREAK_OR_GOTO.MULTIPLE.2012

Iteration statement has more than one break or goto for loop termination.

MISRA C 2012 Rule 15.4: There should be no more than one break or goto statement used to terminate any iteration statement

Category: Advisory

Analysis: Decidable, Single Translation Unit

Applies to: C90, C99

Rationale

Restricting the number of exits from a loop helps to minimize visual code complexity. The use of one break or goto statement allows a single secondary exit path to be created when early loop termination is required.

Example

Both of the following nested loops are compliant as each has a single break used for early loop termination.

for ( x = 0; x < LIMIT; ++x )
{
    if ( ExitNow ( x ) )
    {
        break;
    }

    for ( y = 0; y < x; ++y )
    {
      if ( Exit Now ( LIMIT - y ) )
      {
          break;
      }
   }
}

The following loop is non-compliant as there are multiple break and goto statements used for early loop termination.

for ( x = 0; x < LIMIT; ++x )
{
    if ( BreakNow ( x ) )
    {
        break;
    }
    else if ( GotoNow ( x ) )
    {
        goto EXIT;
    }
    else
    {
        KeepGoing ( x );
    }
}

EXIT:
  ;

In the following example, the inner while loop is compliant because there is a single goto statement that can cause its early termination. However, the outer while loop is non-compliant because it can be terminated early either by the break statement or by the goto statement in the inner while loop.

while ( x != 0u )
{
    x = calc_new_x ( );

    if ( x == 1u )
    {
        break;
    }

    while ( y != 0u )
    {
        y = calc_new_y ( );

        if ( y == 1u )
        {
            goto L1;
        }
  }
}

L1:
z = x + y;