How do you understand the use of the string function library? Let's discuss it together! ! !

The previous article introduced you to "Do you know what a delimiter is? How do we define strings with delimiters? ? ? 》, this article continues to introduce you to the use of the string function library:

String processing includes:

String formatting, string splitting and concatenation, string comparison, search and replacement, string interception, filtering, string ASCII, encryption, etc.;

Processing methods : PHP string processing functions, regular expressions.

Regarding the use of the string function library, we demonstrate through code:

<?php
$str = "欢迎来到PHP中文网";
//is_string
//检验变量是否是字符串类型，是返回true，否则返回false
if(is_string($str)){
    echo $str;
}
echo "<hr>";
echo strlen($str);//strlen()返回字符串的长度
echo "<hr>";
echo strtoupper($str);
?>

The running results are as follows:

About strings, Let’s add one more thing: (use curly braces {} to add, delete, modify and check a string), the specific operation code is as follows:

<?php
//使用花括号{}对一个字符串进行增删改查
$a = &#39;I LOVE &#39;;
echo $a{0}; //将字符串看成集合，可以通过在字符串之后使用{}指定所要的字符从0开始的偏移量来查看
echo "<br>";
$a{10}=&#39;Y&#39;;
echo $a;
echo "<hr>";
$b = &#39;i love you&#39;;
$b{6} = &#39;s&#39;;
echo $b;
?>

The running results are as follows:

Recommended learning: "PHP Video Tutorial"

The above is the detailed content of How do you understand the use of the string function library? Let's discuss it together! ! !. For more information, please follow other related articles on the PHP Chinese website!