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PHP string type explanation, PHP string explanation_PHP tutorial

WBOYOriginal: 2016-07-12 08:51:34848browse

PHP string type explanation, php string explanation

PHP supports eight primitive types (types).

Four scalar types:

Two compound types:

Two special types:

String type

A string is a sequence of characters, like "Hello world!".

There are 3 ways to define a string:

1. Single quotation mark definition

The simplest way to define a string is to enclose it in single quotes ('):

<?php
$var_char = '码农教程';
?>

If there are single quotes in the string, you need to use backslash () to escape:

<?php
$var_char = '字符串中包含\'需要转义';
echo $var_char;		//输出：字符串中包含'需要转义
?>

Tip: If a backslash needs to appear before a single quote or at the end of a string, use two backslashes. In other words, the backslash here only escapes the ' character and not other characters.

If you just define a simple string without parsing more content, it is obviously more efficient to use single quotes.

2. Double quotation mark definition

If you define a string with double quotes ("), PHP knows more escape sequences for special characters:

转义序列	说明
n	换行
r	回车
t	水平制表符
[/td>	反斜线
$	美元符号
"	双引号
[0-7]{1,3}	此正则表达式序列匹配一个用八进制符号表示的字符
x[0-9A-Fa-f]{1,2}	此正则表达式序列匹配一个用十六进制符号表示的字符

Example:

<?php
$var_char = "这里有个换行\n这是第二行文字";
?>

Note that the line break in this example refers to the line break in the textual sense. If you need to display the line break in the browser, you need to use the nl2br() function to replace n with df250b2156c434f3390392d09b1c9563.

The most important thing about double-quoted strings is that the variable names will be replaced by variable value parsing:

<?php
$var_char = "这是一些文字";
echo "请打印这些文字：$var_char";	//输出：请打印这些文字：这是一些文字
?>

3. Delimiter definition

The delimiter defines a string using the delimiter syntax (<<<), and provides an identifier after the delimiter, then the defined string, and finally the same identifier ends String definition.

Example:

<?php
$str = <<<EOD
我是用定界符定义字符串的例子
这是其他更多字符
&hellip;&hellip;
EOD;
?>

In this example, EOD is the identifier. The end identifier must start in the first column of the row. Likewise, identifiers must follow the naming rules of any other tag in PHP: they must only contain alphanumeric underscores, and they must start with an underscore or a non-numeric character.

Note: The line where the end identifier is located cannot have any other characters (possibly except a semicolon ;), including line indentation, etc.

Tips: Strings not only refer to several text characters as shown in the example above, but numbers can also be defined as strings or even huge long texts. This is different from the char definition in the database. place.

Original address: http://www.manongjc.com/php/php_string.html

PHP string type explanation, PHP string explanation_PHP tutorial