Selection statements

if

   if (expression)
        statement

• If expression evaluates to non-zero (true), statement is executed.

• If expression evaluates to 0 (false), control passes to the statement following statement.

• The expression must have scalar type.

else

   if (expression1)
      statement1
   else if (expression2)
      statement2
   else
      statement3

• If expression1 is true, statement1 is executed, and control passes to the statement following statement3. Otherwise, expression2 is evaluated.

• If expression2 is true, statement2 is executed, and control passes to the statement following statement3. Otherwise, statement3 is executed, and control passes to the statement following statement3.

• An else is associated with the lexically nearest if that has no else and that is at the same block level.

switch

   switch (expression)
        statement

• Control jumps to or past statement depending on the value of expression.

• expression must have integral type.

• Any optional case is labeled by an integral constant expression.

• If a default case is present, it is executed if no other case match is found.

• If no case matches, including default, control goes to the statement following statement.

• If the code associated with a case is executed, control falls through to the next case unless a break statement is included.

• Each case of a switch must have a unique constant value after conversion to the type of the controlling expression.

   switch (i) {
   case 1:
   case 3:
   	flag = 1;
   	break;
   default:
   	flag = 0;
   }