Decision Control Statements, Break, Continue, Exit, Goto

Decision control structures (also called selection statements)allow to choose the set-of-instruction for execution depending upon an expression truth value.

The main decision control statements are:

1. if-statement
2. if-else Statement
3. Conditional Operator
4. Switch Case

1. if-statement:

  Syntax:

   if(expression i.e condition)
     statement i.e action;

2. if-else Statement:

  Syntax:

   if(expression)
      statement1;
   else
      statement2;

2.1 Nested if-else Statement:

Type 1:   Syntax:    if(expression 1)    {    if(expression 2)       statement 1;    [else       statement 2;]    }    else       body-of-else;    }

Type 2:   Syntax:    if(expression 1)       body-of-if;    else    {    if(expression 2)       statement 1;    [else       statement 2;]    }    }

Type 3:   Syntax:    if(expression 1)    {    if(expression 2)       statement 1;    [else       statement 2;]    }    else    {    if(expression 2)       statement 1;    [else       statement 2;]    }    }

2.2 if-else-if ladder or if-else-if or Nested if:

  Syntax:

   if(expression)
      statement 1;
   else if(expression 2)
      statement 2;
   else if(expression 3)
      statement 3;
     .......
   else
      statement n;

3. Conditional operator:

The conditional operators ? and : are called ternary operators since they take three arguments.

      Syntax:

        expression 1 ? expression 2 : expression 3

      Example:

        y=(x<3 ? 1 : 7);

4. Switch case statement:

C provide a multiple-branch selection statement known as switch.

      Syntax:

switch(expression)
{
case constant 1:statement sequence 1;
break:
case constant 2:statement sequence 2;
break:
.......
.......
case constant n-1:statement sequence n-1;
break;
[default: statement sequence n];
}

Break statement:

Braek statment is used to terminate the execution of a statement block.The next statement block will be executed.

Keyword: break;

When a break ststement is executed in a loop, the repetition of the loop will be terminated.

Continue Statement:

A continue statement is used to transfer the control to the begnning of a statement block.

Keyword: continue;

When a continue statement is executed in loop, the execution is transfer to the beginning of the loop.

exit() :

An exit() function is used to terminate the execution of a C program permanently.

Keyword: exit();

It is a built-in function and is used/called with necessary argument as exit(0);

goto and label:

A goto statement can transfer the program control anywhere in the program.The target point of a goto statement is marked by a label.

Syntax:

goto label;
.....
label: