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 allows two values to be compared, and it produces a boolean value indicating their relationship. A boolean value is either true or false indicating if the claim or relationship is true or false.

==	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 identify the relationship between two values.

Add a line to your program that prints out 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?

Depending on your compiler, you may actually get the boolean values true and false to print out as words on the screen. More likely, you will get integer values, probably 1 for true and 0 for false. In C++, 0 is taken to be false, and strictly speaking, any non-zero value is true (although most compilers like to use the value 1). When reading and reporting the results of this experiment, translate any integers into true and false.

Modify your program so that it

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

Compile and execute your program.

Question #3.4.2: Find values for i and j in each row to make the indicated relationship true:

Relationship	i	j
i < j
i <= j
i == j
i != j
i >= j
i > j

Use your program to find and confirm your values.

Terminology