将用户输入与C中的文本文件进行比较

Question

I need to have a user input a word then compare the word with a text file to see if it is correct. The user has 3 attempts to enter the word before the program terminates. My issue is reading the word from the file I know it's something simple that I have wrong. I should also clarify that the error I'm getting is in the compiler I haven't gotten to the point of being able to compare the strings yet!

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

int main(void)
{
    FILE *fp;
    fp = fopen("secret.txt","r");
    char guess[10];
    const char secret[10];
    int i, c;
    c = getc(fp);
    fgets(secret, sizeof(secret), fp);

    for (i=0; i < 3; i++)
    {
        printf("Please guess the word: \n");
        scanf("%s", guess);

        while (c !=EOF)
        {   
            if (strcmp(secret,guess)==0)
            {
                printf("Your guess was correct");
                return 0;
            }
            else
            {
                printf("Your guess was incorrect. Please try again\n");
            }
        } 
        fclose (fp);
    }
    return 0;
}

Answer 1

Here are some pointers:

1. c = getc(fp) consumes the first character of the file, so it never becomes part of the secret variable.
2. If secret.txt contains a newline, the newline is read into the secret variable.
3. The while (c != EOF) loop seems pointless, since c isn't modified inside the loop. Furthermore, the infinite nature of the loop prevents the outer for loop from functioning correctly.

If I were you, I'd fix the while loop and would make sure that secret is read correctly, for example by printing it out or examining it in a debugger.

Answer 2

What is

c = getc(fp);

needed for? My "guess" would be that you read the first character of the word into c and then secret misses the first character.

EDIT: Instead of using getc for EOF checking, which as said corrupts the read word (and this while loop is rubbish anyway), just check the return value of fgets :

if(fgets(secret, sizeof(secret), fp) == NULL)
    //file is empty or other error occurred

and remove this infinite while(c != EOF) loop.

So it should rather look something like:

FILE *fp = fopen("secret.txt","r");
char guess[10];
const char secret[10];
int i;
if(fgets(secret, sizeof(secret), fp) == NULL)
{
    printf("Error while reading file\n");
    return -1;
}
fclose(fp);

for (i=0; i < 3; i++)
{
    printf("Please guess the word: \n");
    scanf("%s", guess);
    if (strcmp(secret,guess) == 0)
    {
        printf("Your guess was correct");
        return 0;
    }
    else
        printf("Your guess was incorrect. Please try again\n");
}
return 0;

Answer 3

Your code is grossly off: you do not alter 'c' inside a loop, making it spin indefinitely. It's a good idea to sketch your algorithm on a piece of paper before you start coding. In your case, pseudocode should look like this:

• Open file
• Read the secret
• Close file
• Repeat three times:
• --- Display the prompt
• --- Read user input
• --- If user input matches the secret, congratulate the user and exit.
• Tell the user his guess was incorrect.

At this point, converting it to C should be more or less mechanical. Good luck!

Answer 4

while (c !=EOF)
{   
    if (strcmp(secret,guess)==0)
    {
        printf("Your guess was correct");
        return 0;
    }
    else
    {
        printf("Your guess was incorrect. Please try again\n");
    }
} 

looks like an infinite loop to me