Lab 3: Experiment 4

Relational Expressions

In addition to the arithmetic operators, C++ provides a variety of other operators including six relational operators. A relational operator comparess two values and produces a boolean value true or false indicating their relationship.

==	equality, returns true if and only if its operands are equal
!=	inequality, returns true if and only if its operands are different
<	less-than, returns true if and only if its left operand is less than its right operand
>	greater-than, returns true if and only if its left operand is greater than its right operand
<=	less-than-or-equal-to, returns true if and only if its left operand is not greater than its right operand
>=	greater-than-or-equal-to, returns true if and only if its left operand is not less than its right operand

In C++, a boolean value is represented by the bool type, so these operators produce a bool value. They are called the relational operators because they are used to determine the relationship between two values.

Add the following statement to your program to output these boolean values:

     cout << "true is " << true << "\n"
          << "false is " << false << endl;

Question #3.4.1: What does your program display for this output statement?

With your version of C++, you may actually see the boolean values true and false output as words on the screen. However, it is more likely that you will see integer values, probably 0 for false and 1 for true. In C++, 0 is interpreted as false and any non-zero value as true (although most compilers use the value 1).

Now insert

<< boolalpha

after cout in the preceding output statement. Then compile and execute your program.

Question #3.4.2: What does your program display for this modified output statement?

Now modify your program so that it

• Reads in values for i and j from the keyboard.
• Displays the results of comparing i and j using each of the relational operators listed above.

Compile and execute your program.

Question #3.4.3: Find values for i and j in each row to make the indicated relationship true:

	Relational Expression	i	j
a.	i < j
b.	i <= j
c.	i == j
d.	i != j
e.	i >= j
d.	i > j

Use your program to confirm your values.