Question

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

int main()
{
clrscr();
char username[15], password[15], ch, usr[15], pass[15];
int choice, i=0, found=0;

    printf("1.Add Admin");
    printf("\n2.Log-in Admin");
    printf("\n3.Exit");
    printf("\nEnter your choice: ");
    scanf("%d",&choice);

    switch(choice)
    {
     case 1: FILE *acc;
        if((acc = fopen("c:\\account.txt","a+")) == NULL)
            printf("FILE NOT FOUND!");
        else
            {
            do
             {
              fscanf(acc,"%s %s%",username, password);
             }while(!feof(acc));
            }
        printf("\nEnter desired username: ");
        scanf("%s",username);
        printf("Enter desired password: ");

        while(ch != 13)
        {
         ch = getch();
         password[i] = ch;
         i++;
         printf("*");
        }
        password[i]='\0';
        fprintf(acc,"%s %s\n",username,password);
        fclose(acc);break;
     case 2: FILE *log;
        log = fopen("c:\\account.txt","r");

        printf("Username: ");   //user input username and password//
        scanf("%s",usr);
        printf("Password: ");

        while(ch != 13)
            {
            ch = getch();
            pass[i] = ch;
            i++;
            printf("*");
            }
            pass[i]='\0';
        while(!feof(log)&& found == 0)
        {
         fscanf(log,"%s %s",username,password);     //this is where i am having some problem//
         if(strcmp(usr,username) == 0 && strcmp(pass,password)); 
         found = 1;
         if(found == 1)
            printf("\nWelcome!");
         else
            printf("\nInvalid username or password");

        }

        fclose(log);
    }
getch();
return(0);
}

我无法进行验证工作，即使用户名和密码错误，也总是表示欢迎。如何将用户输入字符串与文件内的数据进行比较？不幸的是，turbo c是必需的。

Answer 1

在比较用户名和密码时，在代码中

if(strcmp(usr,username) == 0 && strcmp(pass,password));

在密码的strcmp处，检查是否已返回0。试试这个

if(strcmp(usr,username) == 0 && strcmp(pass,password) == 0)

并且，您的if循环最后有一个;，这意味着found = 1不在if循环内，删除了; < / p>

Answer 2

当前密码输入包括密码中的换行符，当通过fscanf检索密码时，省略换行符。
为两个密码输入尝试此密码输入

printf("Enter desired password: ");
i = 0;  // to be safe set i to zero                         
while( ( ch = getch()) != '\n') // newline will be detected here and not added to password
{                    
    password[i] = ch;
    i++;        
    printf("*");
    if ( i >= 14) { // to prevent a long password overwriting the array
        break;
    }
}                                        
password[i]='\0';

编辑：
＆＃39; \ n＆＃39;在linux和gcc上为我工作得很好。使用turbo c时，您可能需要使用而不是＆＃39; \ n＆＃39; 13，你必须开始，或者可能＆＃39; \ r＆＃39; 如果文件中有多组用户/密码，您将看到每个集的欢迎/无效消息，因为该消息位于从文件读取的while循环内。
尝试此操作从文件中读取并验证用户/密码

found = 0;
while( ( fscanf(log," %s %s",username,password == 2) {
{             
    if(strcmp(usr,username) == 0 && strcmp(pass,password) == 0)
    {         
        found = 1;
        break;
    }         
}             
if(found == 1) // moved outside while loop so it is seen only once
    printf("\nWelcome!");
else          
    printf("\nInvalid username or password");

用户名和密码验证turbo c

2 个答案: