How to write code to reverse a string in the C language?

Here is an example code in C language to reverse a string.

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

void reverseString(char* str) {
    int length = strlen(str);
    int i, j;
    char temp;
    
    for (i = 0, j = length - 1; i < j; i++, j--) {
        temp = str[i];
        str[i] = str[j];
        str[j] = temp;
    }
}

int main() {
    char str[100];
    
    printf("请输入一个字符串: ");
    gets(str);
    
    reverseString(str);
    
    printf("反转后的字符串: %s\n", str);
    
    return 0;
}

In the code above, we first define a reverseString function that takes a string parameter, str, and reverses the string by swapping its characters. In the main function, we input a string, call the reverseString function to reverse the string, and output the result.