Detailed explanation of strncmp function usage

The strncmp function is a string comparison function. Its function syntax is "int strncmp (const char * str1, const char * str2, size_t n);". Its function is to compare str1 and str2.

The strncmp function is a string comparison function. The comparison of string sizes is determined by the order on the ASCII code table, and this order is also the value of the characters. Its function declaration is int strncmp (const char * str1, const char * str2, size_t n); the function is to compare str1 and str2, up to the first n bytes. If the first n characters of str1 and str2 are the same, then Returns 0; if s1 is greater than s2, returns a value greater than 0; if s1 is less than s2, returns a value less than 0.

strncmp syntax

Function declaration

int strncmp(const char *str1, const char *str2, size_t n)

Parameters

str1--The first string to be compared.

str2-- The second string to be compared.

n--The maximum number of characters to compare.

Return value

The return value of this function is as follows:

If the return value is 866fe35429e2f8b198d8d6bb79bd8e8f 0, it means str2 is less than str1.

If the return value = 0, it means str1 is equal to str2.

Function comparison

The function strncmp is very similar to the function strcmp, but the functions are not exactly the same. The differences are as follows:

(1) The strncmp function

is used Compare the first n characters of s1 and s2 strings. If the two strings are equal, strncmp will return 0. If s1 is a substring of s2, s1 is less than s2.

(2) strcmp function

is also used to compare two strings. Let the two strings be str1, str2

If str1==str2, return Zero;

If str1 > str2, a positive number is returned;

If str1 5949aae7ccfef9278c18e417f04cc69c0. If str1 is equal to str2, the return value is = 0, len refers to the number of characters compared between str1 and str2. The function of this function is to compare the first len ​​characters of string str1 and str2. [5]

Tip: This function is case-sensitive.

Example:

<?php
$str1="Ilikephp!";
$str2="ianfine!";
echo strncmp($str1,$str2,2);
?>

The result is: -1

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