views:

192

answers:

4

I need to read and print data from a file.
I wrote the program like below,

#include<stdio.h>
#include<conio.h>
int main(void)
{
char item[9], status;

FILE *fp;

if( (fp = fopen("D:\\Sample\\database.txt", "r+")) == NULL)
{
    printf("No such file\n");
    exit(1);
}  

 if (fp == NULL)
{
    printf("Error Reading File\n");
}

while(fscanf(fp,"%s %c",item,&status) == 1)  
{  
       printf("\n%s \t %c", item,status);  
}  
if(feof(fp))  
{            
         puts("EOF");     
}  
else  
{  
 puts("CAN NOT READ");  
}  
getch();  
return 0;  
}  

the database.txt file contains
Test1 A
Test2 B
Test3 C

When I run the code, it prints

CAN NOT READ.

Please help me to find out the problem.

+1  A: 

fscanf will treat 2 arguments, and thus return 2. Your while statement will be false, hence never displaying what has been read, plus as it has read only 1 line, if is not at EOF, resulting in what you see.

Didier Trosset
+10  A: 

First of all, you're testing fp twice. so printf("Error Reading File\n"); never gets executed.

Then, the output of fscanf should be equal to 2 since you're reading two values.

Hamid Nazari
+1  A: 

In your code:

while(fscanf(fp,"%s %c",item,&status) == 1)  

why 1 and not 2? The scanf functions return the number of objects read.

anon
A: 

scanf() and friends return the number of input items successfully matched. For your code, that would be two or less (in case of less matches than specified). In short, be a little more careful with the manual pages:

#include <stdio.h>
#include <errno.h>

int main(void)
{
    char                    item[9], status;

    FILE                   *fp;

    if((fp = fopen("D:\\Sample\\database.txt", "r+")) == NULL) {
        printf("No such file\n");
        exit(1);
    }

    while(42) {
        int                     ret = fscanf(fp, "%s %c", item, &status);
        if(ret == 2)
            printf("\n%s \t %c", item, status);
        else if(errno != 0) {
            perror("scanf:");
            break;
        } else if(ret == EOF) {
            break;
        } else {
            printf("No match.\n");
        }
    }
    printf("\n");
    if(feof(fp)) {
        puts("EOF");
    }
    return 0;
}
Michael Foukarakis
Thanks :) //while(42)What it means?
Guru
It's equivalent to `while(1)` or in pseudocode `while(true)`.
Michael Foukarakis