if ( age>=21 && credit>=10000 )

Range Testing

A 24 year old customer with $0 credit could not rent a car. The logical expression would look like this:

age >= 21 && credit >= 10000
---------    ---------------
  true            false
    ----------------
          false

true AND false is false.

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Welter Weight Boxing

A "welter weight" boxer must weight between 136 and 147 pounds. A boxer's weight is tested before each fight to be sure that he is within his weight category. Here is a program that checks if a welter weight boxer's weight is within range:

// Ringside Weigh-in
//
//   Boxer must weigh between 136 and 147 pounds
//
import java.io.*;

class Ringside
{
  public static void main (String[] args) throws IOException
  { 
    BufferedReader stdin = 
        new BufferedReader ( new InputStreamReader( System.in ) );
 
    String inData;
    int    weight; 

    // get the weight
    System.out.println("How heavy is the boxer?");
    inData   = stdin.readLine();
    weight   = Integer.parseInt( inData ); 

    // check that the weight is within range
    if ( _______________________ )
      System.out.println("In range!" );
    else
      System.out.println("Out of range." );
  }
}