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Control statements

Control statements determine the order in which nested statements are executed. In the following, b denotes a boolean expression, i is a variable of any simple type and s, s1 and s2 are single statements. Where more than one statement is required in a control structure, a block should be used.

   if (b) s1;           // if b is true, s1 is executed

   if (b) s1; else s2;  // if b is true, s1 is executed, but
                        // if b is false, s2 is executed

   if (b)
   {
      // executed only if b is true
      s1;
      s2;
   }

   if (b)
   {
      // executed only if b is true
      s1;
      s2;
   }
   else
   {
      // executed only if b is false
      s3;
      s4;
   }

SWITCH

   switch (i)
   {
      case i1:
         s1;      // s1, s2 executed if i == i1
         s2;
         break;

      case i2:
         s3;      // s3 executed if i == i2
         break;

      // ... more cases as required

      default:
         s4;      // s4 executed only if none of the cases matches
         break;
   }

i1 and i2 are constants of the same type as variable i, which must be an integral type.

WHILE

   while (b) s1;  // s1 executed repeatedly while b is true

   while (b)      // s1, s2 executed repeatedly while b is true
   {
      s1;
      s2;
   }

Note that if b is false, s1 or s1 and s2 will not be executed at all.

DO...WHILE

   do s1; while (b);    // s1 executed repeatedly until b is false

   do                   // s1, s2 executed repeatedly until b is false
   {
      s1;
      s2;
   }
   while (b);

Note that s1 or s1 and s2 are executed at least once (even if b is false).

FOR

   for (s_initialisation; e_boolean; s_increment)
   {
      s1;
      s2;
   }

is equivalent to (but clearer in intent than):

   s_initialisation;
   while (e_boolean)
   {
      s1;
      s2;

      s_increment;
   }

for example:

   for (int i = 0; i < 20; i++)
   {
      s1;      // s1, s2 executed 20 times
      s2;      //   with i = 0 ... i = 19
   }

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