Friday, July 10, 2020

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:

No comments:

Post a Comment