How to use the functions in the string.h of the C language?

In the C language, functions in the string.h header file can be used to manipulate strings. Here are some commonly used functions and their usage methods:

1. Copy the string src to the string dest.

#include <string.h>

int main() {
    char str1[10];
    char str2[10] = "Hello";
    
    strcpy(str1, str2);
    printf("%s\n", str1);  // 输出: Hello
    
    return 0;
}

1. append the string src to the end of the string dest.

#include <string.h>

int main() {
    char str1[20] = "Hello";
    char str2[10] = " World";
    
    strcat(str1, str2);
    printf("%s\n", str1);  // 输出: Hello World
    
    return 0;
}

1. Get the length of the string.

#include <string.h>

int main() {
    char str[10] = "Hello";
    
    int len = strlen(str);
    printf("%d\n", len);  // 输出: 5
    
    return 0;
}

1. The function strcmp() compares two strings. It returns 0 if the strings are equal, a value greater than 0 if str1 is greater than str2, and a value less than 0 if str1 is less than str2.

#include <string.h>

int main() {
    char str1[10] = "Hello";
    char str2[10] = "Hello";
    
    int result = strcmp(str1, str2);
    printf("%d\n", result);  // 输出: 0
    
    return 0;
}

These functions are just a part of string.h; there are many other functions available for string operations. Depending on your specific needs, you can refer to the relevant documentation to learn about more functions that can be used.