Nested IF and ELSE IF Ladder

iii. Nested IF....ELSE
General Form:

if(conditional-expression)
{
    if(conditional-expression)
    {
        statements;
    }
    else
    {
        statements;
    }
    statements;
}
else
{
    if(conditional-expression)
    {
        statements;
    }
    statements;
}

In Nested if ..... else, the if and else part can contain one or more if else statements.

Sample Program : Find the largest among three input numbers.

   1:  #include<stdio.h>

   2:  #include<conio.h>

   3:  void main()

   4:  {

   5:      int a,b,c;

   6:      clrscr();

   7:      printf("Enter two numbers : ");

   8:      scanf("%d%d,%d",&a,&b,&c);

   9:      if(a>b)

  10:      {

  11:          if(a>c)

  12:          {

  13:              printf("%d is largest",a);

  14:          }

  15:          else

  16:          {

  17:              printf("%d is largest",c);

  18:          }

  19:      }

  20:      else

  21:      {

  22:          if(b>c)

  23:          {

  24:              printf("%d is largest",b);

  25:          }

  26:          else

  27:          {

  28:              printf("%d is largest",c);

  29:          }

  30:      }

  31:      getch();

  32:  }

iv. ELSE .... IF LADDER
General Form:

if(test condition)
{

}
else if(condition)
{

}
else if(condition)
{

}
else
{

}

This construct is known as the else if ladder.  The conditions are evaluated from the top of the ladder downwards.  As soon as a true condition is found, the statement associated with it is executed skipping the rest of the ladder.

Sample Program : Program to read two numbers and an operator which performs the specified operation and display the result.

   1:  #include<stdio.h>

   2:  #include<conio.h>

   3:  void main( )

   4:  {

   5:     float a,b,res;

   6:     char op;

   7:     clrscr( );

   8:     printf("Enter two Numbers : ");

   9:     scanf("%d%d",&a,&b);

  10:     printf("Enter the Operator : ");

  11:     scanf("%c",&op);

  12:     if(op=='+')

  13:          res=a+b;

  14:     else if(op=='-')

  15:          res=a-b;

  16:     else if(op=='*')

  17:          res=a*b;

  18:     else if(op=='/')

  19:          res=a/b;

  20:     else

  21:     {

  22:          printf("Invalid Operator ! \n Press any key to exit...");

  23:          getch( );

  24:          exit(0);

  25:     }

  26:     printf("%.2f %c %.2f = %.2f",a,op,b,res );

  27:     getch( );

  28:  }