Usage of strlen function in c language

The strlen function is used to get the length of a string. It returns the number of characters in the string that does not contain the null terminator. Usage: strlen(str), where str is the string whose length is to be determined.

Strlen function in C language

Question: What is strlen function?

Answer: The strlen function is a function in C language used to obtain the length of a string.

Usage

strlen The function prototype is as follows:

size_t strlen(const char *str);

Parameters:

• str: The string whose length is to be determined. It must be null terminated.

Return value:

• Returns the number of characters in the string str excluding the null terminator.

Use Cases

The following are some examples of using the strlen function:

#include <stdio.h>
#include <string.h>

int main() {
    char str[] = "Hello World!";
    int len = strlen(str);

    printf("String length: %d\n", len);  // 输出 12

    return 0;
}

Note:

• The strlen function can only be calculated up to the up to a null character.
• If the string str is empty (length is 0), the strlen function returns 0.
• strlen function returns the length in characters instead of bytes.
• The strlen function cannot be used to calculate the length of Unicode strings. You can use the wcslen function to calculate the length of a Unicode string.

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