The difference between PHP strcmp, strnatcmp, and strncmp functions, strnatcmpstrncmp_PHP tutorial

The difference between PHP strcmp, strnatcmp, strncmp functions, strnatcmpstrncmp

String comparison instructions
When s1
When s1=s2, return value = 0
When s1>s2, return positive number

<span> 1</span> <?<span>php
</span><span> 2</span> <span>$str1</span> = 'str100'<span>;
</span><span> 3</span> <span>$str2</span> = 'str20'<span>;
</span><span> 4</span> <span>echo</span> <span>strcmp</span>(<span>$str1</span>, <span>$str2</span>)."<br>"<span>;
</span><span> 5</span> <span>//输出</span><span>-1</span>
<span> 6</span> <span>echo</span> <span>strnatcmp</span>(<span>$str1</span>, <span>$str2</span>)."<br>"<span>;
</span><span> 7</span> <span>//输出</span><span>1</span>
<span> 8</span> <span>echo</span> <span>strncmp</span>(<span>$str1</span>, <span>$str2</span>, 5)."<br>"<span>;
</span><span> 9</span> <span>//输出</span><span>-1</span>
<span>10</span> 
<span>11</span> ?>

The strcmp(str1, str2) function compares two strings according to characters, that is, the two strings are compared character by character from left to right (compared according to the ASCII value) until different characters appear or '

The strnatcmp(str1, str2) function uses the natural sorting algorithm to compare strings. This function implements a comparison algorithm that sorts numeric strings based on human habits. This is the "natural order".

The comparison principle of strncmp(str1, str2, len) function is similar to that of strcmp(str1, str2) function. The difference is that it only compares the len characters at the beginning of the string.

ps: The above three functions are all case-sensitive. If the compared strings are not case-sensitive, there are three other similar functions: strcasecmp, strnatcasecmp, strncasecmp.

String comparison functions strcmp() and strncmp()

Compare:

Function prototype: extern int strcmp(const char *s1, const char * s2);

int strncmp(char *str1, char *str2, int maxlen);
You can see that there are many strncmp One parameter maxlen, the difference is here, this represents the character of the first maxlen length of the comparison string

The return value of the two is also different:
strcmp, when s1 When s1==s2, return 0
When s1>s2, return a positive number
strncmp: If the previous maxlen bytes are completely equal, the return value = 0;
If the previous maxlen bytes are equal During the comparison process, if str1[n] and str2[n] are not equal, (str1[n]-str2[n]) will be returned.

String comparison functions strcmp() and strncmp()

Function: int strcmp (const char *s1, const char *s2)

This function is used to compare the s1 and s2 strings. This function will return a value whose sign is different from the first pair of characters. The comparison results are relevant.

If the two strings are equal, strcmp will return 0.
If s1 is a substring of s2, s1 is less than s2
In addition, there is also the function
int strncmp (const char *s1, const char *s2, size_t size)
This function is extremely similar to strcmp similar. The difference is that the strncmp function specifies to compare size characters. That is, if the first size characters of strings s1 and s2 are the same, the function returns a value of 0.

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www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/887684.htmlTechArticleThe difference between PHP strcmp, strnatcmp, strncmp functions, strnatcmpstrncmp string comparison description when s1s2, return a negative number when s1 =s2, return value = 0 when s1s2, return positive number 1 ? php 2 $st...