A Boolean expression is an expression that results in a Boolean value, that is, either `true` or `false`.

A simple Boolean expression is written as

`Operand1   Comparison Operator   Operand2`

where

• `Operand1 `and` Operand2` can be values, variables or mathematical expressions
• `Comparison Operator `can be one of those shown in the next table

## PHP

 PHP Comparison Operator Description == Equal (not assignment) != Not equal > Greater than < Less than >= Greater than or equal to <= Less than or equal to

Notice: A very common mistake that novice programmers make when writing PHP programs is to confuse the assignment operator with the equal operator. They frequently make the mistake of writing `\$x = 5 `when they actually want to say `\$x == 5`.

Here are some examples of Boolean expressions in PHP:

• `\$x == 5` . This can be read as “test if `\$x` is equal to 5
• `\$x > \$y`. This can be read as “test if `\$x` is greater than `\$y`
• `\$x <= \$y`. This can be read as “test if `\$x` is less than or equal to `\$y`
• `\$x != 3 * \$y + 4`. This can be read as “test if `\$x` is not equal to the result of the expression `3 * \$y + 4`
• `\$s == "Hello"`. This can be read as “test if` \$s` is equal to the word ‘Hello’”

Notice: For humans, Boolean expressions should be interpreted as questions. They should be read as “Is something equal to/greater than/less than something else?” and the answer is just a “Yes” or a “No” (`true `or `false`).

Moreover, given that a Boolean expression actually returns a value (`true `or `false`), this value can be directly assigned to a variable. For example, the expression

`\$a = \$x > \$y;`

assigns a value of `true `or `false` to variable` \$a`. It can be read as “If the content of variable `\$x` is greater than the content of variable `\$y`, assign the value true to variable `\$a`; otherwise, assign the value false.” This next example displays the number 1 on the screen.

```<?php
\$x = 8;
\$y = 5;
\$a = \$x > \$y;

echo \$a;
?>
```

Notice: Please note that in PHP, the Boolean value true can also be represented by the value of 1.

## Java

 Java Comparison Operator Description == Equal (not assignment) != Not equal > Greater than < Less than >= Greater than or equal to <= Less than or equal to

Notice: A very common mistake that novice programmers make when writing Java programs is to confuse the assignment operator with the equal operator. They frequently make the mistake of writing `x = 5 `when they actually want to say `x == 5`.

Remember: In Java, in order to test if two strings are lexicographically equal, you need to use the `equals() `method. For example, the statement `a.equals(b)` tests if the content of the string variable` a `is equal to the content of string variable` b`.

Remember: In Java, in order to test if one string is lexicographically “greater” or “less” than another string, you need to use the `compareTo() `method. For example, the statement `a.compareTo(b) `compares the content of the string variable` a `to the content of string variable` b `and returns a value greater than 0 if variable` a `is lexicographically greater than variable `b`, or a value less than 0 if variable` a` is lexicographically less than variable` b`.

Here are some examples of Boolean expressions in Java:

• `x == 5` . This can be read as “test if `x` is equal to 5
• `x > y`. This can be read as “test if `x` is greater than `y`
• `x <= y`. This can be read as “test if `x` is less than or equal to `y`
• `x != 3 * y + 4`. This can be read as “test if `x` is not equal to the result of the expression `3 * y + 4`
• `s.equals("Hello") == true`. This can be read as “test if `s` is equal to the word ‘Hello’”

Notice: For humans, Boolean expressions should be interpreted as questions. They should be read as “Is something equal to/greater than/less than something else?” and the answer is just a “Yes” or a “No” (`true `or `false`).

Moreover, given that a Boolean expression actually returns a value (`true `or `false`), this value can be directly assigned to a variable. For example, the expression

`a = x > y;`

assigns a value of `true `or `false` to variable` a`. It can be read as “If the content of variable `x` is greater than the content of variable `y`, assign the value true to variable `a`; otherwise, assign the value false.” This next example displays the number` true` on the screen.

```public static void main(String[] args) throws java.io.IOException {
int x, y;
boolean a;

x = 8;
y = 5;
a = x > y;

System.out.println(a);
}

```

## C++

 C++ Comparison Operator Description == Equal (not assignment) != Not equal > Greater than < Less than >= Greater than or equal to <= Less than or equal to

Notice: A very common mistake that novice programmers make when writing C++ programs is to confuse the assignment operator with the equal operator. They frequently make the mistake of writing `x = 5 `when they actually want to say `x == 5`.

Here are some examples of Boolean expressions in C++:

• `x == 5` . This can be read as “test if `x` is equal to 5
• `x > y`. This can be read as “test if `x` is greater than `y`
• `x <= y`. This can be read as “test if `x` is less than or equal to `y`
• `x != 3 * y + 4`. This can be read as “test if `x` is not equal to the result of the expression `3 * y + 4`
• `s == "Hello"`. This can be read as “test if `s` is equal to the word ‘Hello’”

Notice: For humans, Boolean expressions should be interpreted as questions. They should be read as “Is something equal to/greater than/less than something else?” and the answer is just a “Yes” or a “No” (`true `or `false`).

Moreover, given that a Boolean expression actually returns a value (`true `or `false`), this value can be directly assigned to a variable. For example, the expression

`a = x > y;`

assigns a value of `true `or `false` to variable` a`. It can be read as “If the content of variable `x` is greater than the content of variable `y`, assign the value true to variable `a`; otherwise, assign the value false.” This next example displays the number` true` on the screen.

```#include <iostream>
using namespace std;
int main() {
int x, y;
bool a;

x = 8;
y = 5;
a = x > y;

cout << a;
return 0;
}
```

## C#

 C# Comparison Operator Description == Equal (not assignment) != Not equal > Greater than < Less than >= Greater than or equal to <= Less than or equal to

Notice: A very common mistake that novice programmers make when writing C# programs is to confuse the assignment operator with the equal operator. They frequently make the mistake of writing `x = 5 `when they actually want to say `x == 5`.

Remember: In C#, in order to test if one string is lexicographically “greater” or “less” than another string, you need to use the `CompareTo() method`. For example, the statement `a.CompareTo(b) `compares the content of the string variable` a `to the content of string variable` b `and returns a value greater than 0 if variable` a `is lexicographically greater than variable `b`, or a value less than 0 if variable` a `is lexicographically less than variable` b`.

Here are some examples of Boolean expressions in C#:

• `x == 5` . This can be read as “test if `x` is equal to 5
• `x > y`. This can be read as “test if `x` is greater than `y`
• `x <= y`. This can be read as “test if `x` is less than or equal to `y`
• `x != 3 * y + 4`. This can be read as “test if `x` is not equal to the result of the expression `3 * y + 4`
• `s == "Hello"`. This can be read as “test if `s` is equal to the word ‘Hello’”

Notice: For humans, Boolean expressions should be interpreted as questions. They should be read as “Is something equal to/greater than/less than something else?” and the answer is just a “Yes” or a “No” (`true `or `false`).

Moreover, given that a Boolean expression actually returns a value (`true `or `false`), this value can be directly assigned to a variable. For example, the expression

`a = x > y;`

assigns a value of `true `or `false` to variable` a`. It can be read as “If the content of variable `x` is greater than the content of variable `y`, assign the value true to variable `a`; otherwise, assign the value false.” This next example displays the number` true` on the screen.

```static void Main() {
int x, y;
bool a;

x = 8;
y = 5;
a = x > y;

Console.Write(a);
}

```

## Visual Basic

 VB Comparison Operator Description = Equal <> Not equal > Greater than < Less than >= Greater than or equal to <= Less than or equal to

Remember: In Visual Basic, in order to test if one string is lexicographically “greater” or “less” than another string, you need to use the `CompareTo() `procedure. For example, the statement `a.CompareTo(b) `compares the content of the string variable` a `to the content of string variable` b `and returns a value greater than 0 if variable` a `is lexicographically greater than variable `b`, or a value less than 0 if variable` a `is lexicographically less than variable` b`.

Here are some examples of Boolean expressions in Visual Basic:

• `x = 5` . This can be read as “test if `x` is equal to 5
• `x > y`. This can be read as “test if `x` is greater than `y`
• `x <= y`. This can be read as “test if `x` is less than or equal to `y`
• `x <> 3 * y + 4`. This can be read as “test if `x` is not equal to the result of the expression `3 * y + 4`
• `s = "Hello"`. This can be read as “test if `s` is equal to the word ‘Hello’”

Notice: For humans, Boolean expressions should be interpreted as questions. They should be read as “Is something equal to/greater than/less than something else?” and the answer is just a “Yes” or a “No” (`true `or `false`).

Moreover, given that a Boolean expression actually returns a value (`true `or `false`), this value can be directly assigned to a variable. For example, the expression

`a = x > y`

assigns a value of `true `or `false` to variable` a`. It can be read as “If the content of variable `x` is greater than the content of variable `y`, assign the value true to variable `a`; otherwise, assign the value false.” This next example displays the number` true` on the screen.

```Sub Main()
Dim x, y As Integer
Dim a As Boolean

x = 8
y = 5
a = x > y

Console.Write(a)

End Sub
```

## Python

 Python Comparison Operator Description == Equal (not assignment) != Not equal > Greater than < Less than >= Greater than or equal to <= Less than or equal to

Notice: A very common mistake that novice programmers make when writing Python programs is to confuse the assignment operator with the equal operator. They frequently make the mistake of writing `x = 5 `when they actually want to say `x == 5`.

Here are some examples of Boolean expressions in Python:

• `x == 5` . This can be read as “test if `x` is equal to 5
• `x > y`. This can be read as “test if `x` is greater than `y`
• `x <= y`. This can be read as “test if `x` is less than or equal to `y`
• `x != 3 * y + 4`. This can be read as “test if `x` is not equal to the result of the expression `3 * y + 4`
• `s = "Hello"`. This can be read as “test if `s` is equal to the word ‘Hello’”

Notice: For humans, Boolean expressions should be interpreted as questions. They should be read as “Is something equal to/greater than/less than something else?” and the answer is just a “Yes” or a “No” (`true `or `false`).

Moreover, given that a Boolean expression actually returns a value (`true `or `false`), this value can be directly assigned to a variable. For example, the expression

`a = x > y`

assigns a value of `true `or `false` to variable` a`. It can be read as “If the content of variable `x` is greater than the content of variable `y`, assign the value true to variable `a`; otherwise, assign the value false.” This next example displays the number` true` on the screen.

```x = 8
y = 5
a = x > y

print(a)

```