How to intercept characters in PHP

PHP is a server-side scripting language widely used in web development. Among them, string is one of the most commonly used data types in PHP. When using strings in PHP, you may encounter the need to intercept characters, and you also need to determine how many strings to count. This article will introduce how to intercept characters in PHP and how to count numbers to count several strings.

1. Intercept characters

In PHP, there are many ways to intercept strings. The following are the three most common methods:

1. substr() function

substr() function can intercept a part of the string and return the intercepted characters string part. The syntax of the function is as follows:

substr(string $string, int $start[, int $length])

Among them, $string represents the string to be intercepted, $start represents the starting position of interception, and $length represents the length of interception. If $length is omitted, the function returns all characters starting at $start and ending at the end of the string.

The following is an example of how to use the substr() function to intercept a string:

$str = "Hello, world!";
$s1 = substr($str, 0, 5);   //截取字符串前5个字符
$s2 = substr($str, 7);      //从第7个字符开始截取到字符串末尾
echo $s1;    //输出结果为：Hello
echo $s2;    //输出结果为：world!

2. mb_substr() function

mb_substr() function It is an interception function used in multi-byte character sets, similar to the substr() function. However, since in multi-byte characters, one character may be composed of multiple bytes, if you use the substr() function to intercept multi-byte characters, garbled characters may occur. Therefore, if you need to intercept multi-byte characters in PHP, it is recommended to use the mb_substr() function.

The syntax of the mb_substr() function is similar to the substr() function. The following is an example of using the mb_substr() function to intercept multi-byte characters:

header("Content-Type:text/html; charset=utf-8");
$str = "你好，世界！";
$s = mb_substr($str, 0, 2, "utf-8");    //截取前两个字符，指定字符编码为utf-8
echo $s;    //输出结果为：你好

3. mb_strimwidth() function

mb_strimwidth() function is used to intercept strings. And add an ellipsis function at the end of the interception. Its syntax is as follows:

mb_strimwidth(string $string, int $start, int $length, string $trimmarker = "", string $encoding = ini_get("mbstring.internal_encoding()"))

Among them, $trimmarker represents the symbol used to indicate omission, and the default is an empty string. $encoding represents the character encoding, which defaults to internal encoding.

The following is an example of using the mb_strimwidth() function:

header("Content-Type:text/html; charset=utf-8");
$str = "PHP是一种广泛应用于Web开发的服务器端脚本语言。";
$s = mb_strimwidth($str, 0, 14, "...", "utf-8");    //截取前14个字符，添加省略号。指定字符编码为utf-8
echo $s;    //输出结果为：PHP是一种广泛应...

2. Numbers count as several strings

In PHP, numbers are regarded as one part of a string form, however, when working with strings, the number should be treated as a character, not a string. Therefore, when performing a truncation operation on a string, the number should be evaluated as a character.

The following is an example that will show how to calculate numbers and several strings in PHP:

$str = "Hello, 1234 world!";
$s1 = substr($str, 0, 5);   //截取前5个字符
$s2 = substr($str, 7, 4);   //截取数字"1234"
echo $s1;    //输出结果为：Hello
echo $s2;    //输出结果为：1234

In this example, the first 5 characters intercepted are "Hello", including 5 characters. When intercepting the number "1234", the number is regarded as one character, so the length is 4 characters.

3. Summary

This article introduces how to intercept characters in PHP and solves the problem of counting numbers into several strings. Strings are a very common data type in PHP, and understanding how to handle strings can help you write efficient PHP code.

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