Selection Statement

Selection Statement

• A selection statement is a control statement that allows choosing between two or more execution paths in a program.
• C provide one-way, two-way and multiple conditional branching execution.
• C provides this branching through two methods namely if statement and switch statement
  

If

• There are three ways of writing if statements.

if
       if(expression){
                Statements;
        }

• The expression is evaluated to either true or false.
  
• True is nonzero value and false is zero value.
  
• The Statements inside the if will only be executed if the expression is evaluated to true

if…else
        if(expression){
                Statements1;
        }else{
                Statements2;
        }

• If the expression is evaluated to true then Statements1 will be executed.
• If the expression is evaluated to false then Statements2 will be executed.
  

if…elseif
        if(expression1){
                Statements1;
        }elseif (expression2{
                Statements2;
        }elseif (expression3){
                Statements3;
        }else{
                Statements4;
        }

Switch Statements

• Switch is a composite statement used to make a decision between many alternatives
• The expression of switch statements must be evaluated to either integer type or character constant.
• The selection condition must be one of the C integral types
  

        switch (expression){
               case constant-1: statement;
                                               …
                                              statement;
                                              break;
               case constant-2: statement;
                                               …
                                              statement;
                                              break;
               case constant-n: statement;
                                               …
                                              statement;
                                              break;
               default                : statement;
                                               …
                                              statement;
                                              break;
         }

• Each case label must be a constant expression either integer or character
• The case label simply provides an entry point to start executing the code
• Default is executed whenever none of the other case values matches the value in the switch expression
• The break statement causes the program to jump out of the switch statement; continue with the code after the switch statement