Which symbols in php do not need to be escaped?

In PHP, we often need to use various symbols for string processing, string concatenation, numerical operations, etc. During these operations, some of our symbols may need to be escaped to be used correctly, while some symbols do not need to be escaped. So which symbols do not need to be escaped? Below, we will introduce them one by one.

1. Underscore (_)
Underscore is usually used as a separator for variable names in PHP, and it can be used directly without escaping. For example, we can use underscores like this:

$first_name = "John";
$last_name = "Doe";
$full_name = $first_name . "_" . $last_name;
echo $full_name;

The result is: John_Doe

2. The period (.)
The period represents the string concatenation character in PHP, and it can be used directly without escaping use. For example, we can use dots like this:

$first_name = "John";
$last_name = "Doe";
$full_name = $first_name . "." . $last_name;
echo $full_name;

The result is: John.Doe

3. Single quotation mark (')
Single quotation mark represents the beginning and end of the string in PHP. If the string Single quotes can be escaped using double quotes or backslashes. However, if you need to include double quotes in a string, single quotes do not need to be escaped. For example:

$quote = 'I said, "Hello, world!"';
echo $quote;

The result is: I said, "Hello, world!"

4. Double quotation marks (")
Double quotation marks also represent the start and end of a string in PHP, but double quotation marks are more flexible than single quotation marks, and you can use variables, escape characters, etc. to expand the string. Similar to single quotes, if you need to include single quotes in a string, double quotes do not need to be escaped. For example:

$name = 'John';
$greeting = "Hello, $name!";
echo $greeting;

The result is: Hello, John!

5. Curly braces ({})
Curly braces are usually used in PHP Specify variable range or represent array subscript, it does not need to be escaped. For example:

$name = 'John';
${$name} = 'Doe';
echo $ John;

The result is: Doe

6. Backslash()
Backslash represents the beginning of the escape character in PHP, and it needs to be escaped before it can be output. However, if we need to include the backslash itself in the string, the backslash does not need to be escaped. For example:

echo "This is a backslash: \";
echo 'This is a backslash too: \';

The result is: This is a backslash: \ This is a backslash too: \

In addition to the above symbols, there are some other symbols in PHP Symbols do not need to be escaped, such as colon (:), semicolon (;), comma (,), etc. In short, when using these symbols, we should escape or not escape according to the actual situation to ensure Code correctness and reliability.

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