The meaning of some symbols in php

PHP is a popular programming language. It is a server-side scripting language commonly used for writing web applications. When writing PHP code, developers will encounter various symbols, which have important grammatical meanings. In this article, we will introduce some commonly used symbols in PHP and their meanings.

1. Semicolon (;)

The semicolon is one of the most commonly used symbols in PHP. It is used to indicate the end of a statement and tell the interpreter that the statement has ended. Each statement must end with a semicolon, otherwise the interpreter will report an error.

For example, the following code uses a semicolon to end a statement:

<?php
echo "Hello, world!";
?>

2. Double quotes (“ ”)

Double quotes in PHP Used to define strings. Double quotes can contain variables, and PHP will parse the variables into their corresponding values. Double quotes also support escape sequences, which allow you to escape special characters with backslash ().

For example, the following code uses double quotes to define a string:

<?php
$name = "Alice";
echo "Hello, $name!";
?>

The output result is: Hello, Alice!

3. Single quotes (' ' )

Single quotes are also used to define strings. Unlike double quotes, variables in single quotes will not be parsed. Special characters within single quotes also cannot use escape sequences.

For example, the following code uses single quotes to define a string:

<?php
$name = "Alice";
echo &#39;Hello, $name!&#39;;
?>

The output result is: Hello, $name!

4. Greater than sign (> ; )

The greater than sign is used in PHP to compare the size of two values. The expression evaluates to true if the value on the left is greater than the value on the right, otherwise it is false.

For example, the following code uses the greater than sign to compare two values:

<?php
$x = 5;
$y = 3;
if ($x > $y) {
  echo "x is greater than y";
} else {
  echo "x is not greater than y";
}
?>

The output result is: x is greater than y

5. Less than sign ( < )

The less than sign is similar to the greater than sign and is also used to compare the size of two values. The expression evaluates to true if the value on the left is less than the value on the right, otherwise it is false.

For example, the following code uses the less than sign to compare two values:

<?php
$x = 5;
$y = 3;
if ($x < $y) {
  echo "x is less than y";
} else {
  echo "x is not less than y";
}
?><p>The output result is: x is not less than y</p>
<ol start="6"><li>Equal sign ( = )</li></ol>
<p>The equal sign is used in PHP to assign a value to a variable. The left side of the equal sign is the variable name, and the right side is the value to be assigned to the variable. </p>
<p>For example, the following code uses the equal sign to assign a value to a variable: </p>
<pre class="brush:php;toolbar:false"><?php
$x = 5;
echo $x; // 输出 5
?>

7. The dot sign (.)

The dot sign is in PHP Used to concatenate two strings. The left and right sides of the dot can be string constants, variables or expressions.

For example, the following code uses dots to connect two strings:

<?php
$first = "Hello";
$last = "World";
echo $first . " " . $last;
?>

The output result is: Hello World

8. curly brackets ({ } )

Curly braces are used in PHP to represent a block of code. The code enclosed in curly braces is treated as a whole and can be executed as a statement, or as a function body or class definition.

For example, the following code uses curly braces to represent the code block of an if statement:

<?php
$x = 5;
if ($x > 0) {
  echo "x is positive";
} else {
  echo "x is negative";
}
?>

The output result is: x is positive

The above are some of the PHP Commonly used symbols and their meanings. Different symbols can be combined to construct various grammatical structures and functions. As a PHP developer, it is crucial to be proficient in the usage of these symbols.

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