if Statement

The 'if' Statement

      The 'if' statement is the simplest form of selection structure. It is a decision making statement. It is used to execute or to ignore a statement or a set of statements after testing a condition.

      The ' if ' statement evaluates the condition. If the given condition is true, the statement or a set of statements following the ' if ' statement is ignored and control transfers to the statement that comes after the 'if' structure.

      The syntax of 'if' statement for a single statement is as follows:

                   if ( condition ) 

                             statement - 1 ;

                   statement - 2 ;

      In the above syntax:

condition         It indicates the test condition. It can be a relational expression or logical expression.

statement-1     It is a single statement which will be executed if the condition is true. If the condition                           is false, statement-1 is ignored.

statement-2     This statement comes after the 'if' structure.

      A set of statements following the 'if' statement can be given. In this case, these statements are written within curly braces { }. The set of statements surrounded by curly braces { } is called compound statement.

      The syntax of 'if' statement for compound statement is as follows:

                 if ( condition )

                 {

                               statement - 1 ;

                               statement - 2 ;

                               - - - - - - - - - -

                               statement - m ;

                 }

                 statement - n ;

      In the above syntax, the set of statements (from statement-1 to statement-m ) represent the compound statement. The statement-n represents the statement that comes after the 'if'  structure.

Flowchart of Simple ' if ' Structure

      The flowchart of 'if' statement is as follows:

Flowchart Of  ' if  ' Statement

Write a program that inputs a number and displays a message if the number is greater than 100.

Example in C

#include < stdio.h >
#include < conio.h >
void main ( )
{
      int   n ;
      printf  ( " Enter a Number " ) ;
      scanf ( " %d " , &n ) ;
      if ( n >= 100 )
          printf ( " Number is greater than 100\n" ) ;
      getch ( ) ;
}

Example in C

#include < iostream >

using namespace std ;

int main ( )

{  

      int   n ;
      cout << " Enter a Number " ;
      cin >> n ;
      if ( n >= 100 )
          cout << " Number is greater than 100 " ;
      return 0;
}