I am comparing user input of usernames and passwords. the string that are being compared to are being read in from a file. For whatever reason, it is appropriately comparing the usernames, but not the passwords.
我正在比较用户输入的用户名和密码。正在比较的字符串正在从文件中读入。无论出于何种原因,它都会适当地比较用户名,而不是密码。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
const int MAX_SIZE = 100;
int main()
{
FILE *fp;
char *filename = "userdata.txt";
char arr[100][MAX_SIZE];
//open for writing
fp = fopen(filename, "r");
//verify open
if(fp == NULL)
{
printf("%s does not exist", filename);
return 0;
}
int index = 0;
//read file into array
while(fgets(arr[index], MAX_SIZE, fp) != NULL)
{
index++;
}
//username input
char username[100];
printf("Username: ");
scanf("%s", username);
//password input
char password[100];
printf("Password: ");
scanf("%s", password);
int check1 = 0;
int check2 = 0;
int x;
for (int i = 0 ; i<index ; i++)
{
char *token = strtok(arr[i], " ");
while (token != NULL)
{
x = strcmp(token,username);
printf("%d\n",x);
printf("%s %s\n",token,username);
if(!strcmp(token,username))
{
check1 = 1;
}
token = strtok(NULL, " ");
x = strcmp(token,username);
printf("%d\n",x);
printf("%s %s\n",token,password);
if(!strcmp(token,username))
{
check2 = 1;
}
token = strtok(NULL, " ");
if(check1&&check2)
{
printf("The amount is: %s\n",token);
return 0;
}
token = strtok(NULL, " ");
check1=0;
check2=0;
}
}
printf("Username/Password mismatch!!!\n");
return 0;
}
console output:
控制台输出:
Username: user1
Password: password1
0
user1 user1
-5
password1 password1
1
user2 user1
-5
password2 password1
2
user3 user1
-5
password3 password1
3
user4 user1
-5
password4 password1
4
user5 user1
-5
password5 password1
5
user6 user1
-5
password6 password1
Username/Password mismatch!!!
更多回答
What is the layout of the file being loaded? Without that detail, this code may be passing a NULL pointer to functions like strcmp()
and printf()
.
正在加载的文件的布局是什么?如果没有这个细节,这段代码可能会将空指针传递给strcMP()和printf()等函数。
优秀答案推荐
When fgets
reads in a line of text, it also reads and stores the newline at the end of the line.
当fget读入一行文本时,它还会读取并存储该行末尾的换行符。
This means that when you split the string with strtok
and use " "
as the delimiter, the read-in password includes the newline, while the password from the user read via scanf
with the %s
format specifier does not, causing the mismatch.
这意味着当您使用strtok拆分字符串并使用“”作为分隔符时,读入密码包括换行符,而通过scanf使用%S格式说明符读取的用户密码不包括换行符,从而导致不匹配。
You can fix this by including the newline character in the set of delimiters given to strtok
.
您可以通过在给strtok的一组分隔符中包含换行符来修复此问题。
char *token = strtok(arr[i], " \n");
...
token = strtok(NULL, " \n");
Also, your second set of calls to strcmp
is checking the username instead of the password. So instead of this:
此外,您对strcMP的第二组调用是检查用户名而不是密码。因此,与其这样,不如:
x = strcmp(token,username);
printf("%d\n",x);
printf("%s %s\n",token,password);
if(!strcmp(token,username))
You want this:
你想要的是:
x = strcmp(token,password);
printf("%d\n",x);
printf("%s %s\n",token,password);
if(!strcmp(token,password))
更多回答
Given that the OP's code suggests there is at least a 3rd parameter (amount
) on the lines read from the file, the suggestion that the 2nd field of the line read with fgets()
contains a LF is not likely to be appropriate.
假设OP的代码表明从文件中读取的行上至少有第三个参数(数量),那么使用fget()读取的行的第二个字段包含LF的建议可能不太合适。
我是一名优秀的程序员,十分优秀!