The role of strlen function in c language

The strlen function is used in C language to calculate the length of a given string (excluding the terminating null character) and return the number of characters in the string. It accepts a string pointer as a parameter and returns an unsigned integer value representing the length of the string.

The role of strlen function in C language

The strlen function is a C language standard library function used for calculations The length of the given string. It returns the number of characters in the string (excluding the terminating null character '\0').

Usage

The syntax of strlen function is as follows:

<code class="c">size_t strlen(const char *str);</code>

where,

• str : The string whose length is to be calculated. It is a pointer to a character array.

Return value

The strlen function return type is size_t, which represents an unsigned integer type, which contains the length of the string.

Example

The following example demonstrates the use of the strlen function:

<code class="c">#include <stdio.h>
#include <string.h>

int main() {
    char str[] = "Hello, world!";
    int len;

    // 计算字符串的长度
    len = strlen(str);

    // 输出字符串的长度
    printf("字符串 '%s' 的长度为：%d\n", str, len);

    return 0;
}</code>

Output:

<code>字符串 'Hello, world!' 的长度为：13</code>

Note:

• The strlen function only counts the number of characters in the string, excluding the terminating null character '\0'.
• If the string passed to the strlen function is NULL, it will return 0.
• The strlen function is defined in the C language standard library, so the header file <string.h> needs to be included before using it.

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