1. Basic concepts of strings in PHP
Strings are a very important type in PHP programming and are a basic data type. A string is composed of a series of characters, which can be represented by single quotes or double quotes. For example:
$str1 = 'hello world'; $str2 = "I'm learning PHP";
Among them, $str1 contains 13 characters, and $str2 contains 15 characters. When using single quotes to represent strings, the variables in the string will not be parsed, for example:
$str3 = 'My name is $name';//输出为:My name is $name
, while double quotes will parse the variables, for example:
$str4 = "My name is $name";//输出为:My name is John
In PHP, String concatenation can use the "." operator, for example:
$str5 = "hello"."world"; //输出为:helloworld
2. Type conversion and string conversion in PHP
Since PHP is a weakly typed language, the type of variables can Implicit conversions are performed as needed. In PHP, you can use casts or automatic type conversions to convert one type to another. For example:
$name = "John"; $age = 25; //使用强制类型转换将年龄转换为字符串 $str6 = (string) $age; //使用自动类型转换将字符串和整数进行拼接 $str7 = $name . $age;
Among them, the value of $str6 is the string "25", and the value of $str7 is the string "John25".
To convert other types of values to strings, you can use the (string) identifier to perform forced type conversion, for example:
$num = 123; $str8 = (string) $num;//输出为:123
Similarly, you can use (int), (float ), (bool) and other identifiers for type conversion.
You can also use functions to convert other types of values into strings, for example:
$num = 123; $str9 = strval($num);//输出为:123
3. Escape and quote marks in PHP
In PHP strings, you must Special characters such as quotation marks or backslashes need to be escaped. For example:
$str10 = "I'm learning PHP"; $str11 = 'My name is \'John\'';
Among them, the single quotes in $str10 must be escaped with backslashes, and the single quotes and backslashes in $str11 must be escaped.
In PHP, a string represented by double quotes can be embedded in a variable, for example:
$name = "John"; $str12 = "My name is $name";//输出为:My name is John
If you want to represent a set of double quotes or single quotes, you can use the escape symbol to escape , for example:
$str13 = "He said \"hello\""; $str14 = 'I\'m learning PHP';
Among them, the double quotes in $str13 and the single quotes in $str14 need to be escaped.
4. Processing long strings in PHP
In PHP, the processing of long strings is one of the issues that need to be considered. When you need to process strings containing large amounts of text or HTML tags, you can use multiline strings to simplify their representation and processing. The two methods are as follows:
$str15 = "Lorem ipsum dolor sit amet, consectetur adipisicing elit.".
"Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.". "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.";
$str16 = "Lorem ipsum dolor sit amet, consectetur adipisicing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.";
$str17 = 'Lorem ipsum dolor sit amet, consectetur adipisicing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.';
Among them, $str15 is equivalent to $str16 and $str17.
5. Processing multi-language strings in PHP
When processing multi-language strings, you can use PHP's built-in gettext() function and related tools for processing. For example:
// 设置语言环境为中文 putenv("LC_ALL=zh_CN"); // 设置本地目录 setlocale(LC_ALL, 'zh_CN'); // 加载语言包 bindtextdomain("myapp", "./locale"); textdomain("myapp"); // 调用gettext()函数 echo _("Hello world");
will output the "Hello world" string in the corresponding language environment.
6. Processing URLs in PHP
When processing URLs, you need to use the urlencode() function to encode special characters in the URL. For example:
$str18 = urlencode("https://example.com/?q=hello world");
Among them, The urlencode() function will convert spaces in the URL into numbers and convert special characters in the URL into %XX format.
7. Conclusion
In PHP, string processing is One of the very important parts. This article introduces the basic concepts of strings, type conversion and string conversion, escaping and quotation marks, processing long strings, processing multi-language strings and related knowledge points of processing URLs. In actual programming , you should choose the appropriate string processing method according to the specific situation, and pay attention to the security and reliability of the string.
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