DevEco Studio 开发一个注册与登录界面代码

你可以参考以下代码：

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

#define MAX_USERNAME_LENGTH 20
#define MAX_PASSWORD_LENGTH 20

typedef struct {
char username[MAX_USERNAME_LENGTH];
char password[MAX_PASSWORD_LENGTH];
} User;

int main() {
User user;
char choice;
FILE *fp;

printf("Welcome to the registration and login system!\n");

while (1) {
printf("\nPlease choose an option:\n");
printf("1. Register\n");
printf("2. Login\n");
printf("3. Exit\n");
printf("Your choice: ");
scanf(" %c", &choice);

switch (choice) {
case '1':
printf("\nPlease enter your username (up to %d characters): ", MAX_USERNAME_LENGTH);
scanf("%s", user.username);
printf("Please enter your password (up to %d characters): ", MAX_PASSWORD_LENGTH);
scanf("%s", user.password);

fp = fopen("users.txt", "a");
fprintf(fp, "%s %s\n", user.username, user.password);
fclose(fp);

printf("\nRegistration successful!\n");
break;

case '2':
printf("\nPlease enter your username: ");
scanf("%s", user.username);
printf("Please enter your password: ");
scanf("%s", user.password);

fp = fopen("users.txt", "r");
while (fscanf(fp, "%s %s", user.username, user.password) != EOF) {
if (strcmp(user.username, user.username) == && strcmp(user.password, user.password) == ) {
printf("\nLogin successful!\n");
break;
}
}
fclose(fp);

if (feof(fp)) {
printf("\nIncorrect username or password. Please try again.\n");
}
break;

case '3':
printf("\nThank you for using the registration and login system!\n");
exit();

default:
printf("\nInvalid choice. Please try again.\n");
break;
}
}

return ;
}