PHP determines whether strings are equal

PHP string comparison functions mainly include strcmp, strcasecmp, strnatcmp, strnatcasecmp, and their usage is basically similar. (Recommended learning: PHP programming from entry to proficiency)

//按字节对字符串进行比较
int strcmp(string str1,string str2)
//同上，但是不区分大小写
int strcasecmp(string str1,string str2)
//按“自然排序”进行比较
int strnatcmp(string str1,string str2)
//同上，但是不区分大小写
int strnatcasecmp(string str1,string str2)

The return results of these four functions are the same

If str1 Equal to str2, return 0

If str1 is greater than str2, return 1

If str1 is less than str2, return -1

Natural sorting and dictionary sorting

Dictionary Sorting: Compare byte by byte according to byte ASCII

Natural sorting: According to human thinking, for example, "2">"11" in byte sorting, while "2"< "11"

Among the previous four comparison functions, you only need to understand what these two sortings are, and you can distinguish the four functions clearly. To give the most intuitive example: comparison of

hello11 ​​and hello2, in dictionary sorting, hello11

<?php
$str1 = &#39;hello11&#39;;
$str2 = &#39;hello2&#39;;
$str3 = &#39;Hello11&#39;;
$str4 = &#39;Hello2&#39;;

echo strcmp($str1,$str2).&#39;<br>&#39;;          //-1
echo strcasecmp($str1,$str3).&#39;<br>&#39;;      //0
echo strnatcmp($str1,$str2).&#39;<br>&#39;;           //1
echo strnatcasecmp($str2,$str4).&#39;<br>&#39;;       //0

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