Why do I get FILE pointer error while checking NULL condition?

Question

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

#define PATH "F:\\c\\projects\\Banking Management System\\data\\"
#define F_PWD "pwd.txt"

#define FILENAME(q1, path, f_)  q1 path f_ q1

void main() {
    printf("\n%s", FILENAME("\"",PATH, F_PWD));

    FILE *fp=fopen(FILENAME("\"",PATH, F_PWD), "w");

    if (fp==NULL){
        perror("\nERROR: ");
        exit(EXIT_FAILURE);
    }

    fprintf(fp,"%d,%s,%f\n",1,"Anil Dhar",1000.00);
    fclose(fp);
}

Problem

The printf shows the correct file name with path: "F:\c\projects\Banking Management System\data\pwd.txt"
However,perror shows: ERROR: Invalid argument
It doesn't create/write into the file, even if, I remove the following condition:

if (fp==NULL){ perror("\nERROR: "); exit(EXIT_FAILURE); }

Why is perror showing "Invalid argument" ?

dbush · Accepted Answer · 2021-11-11 02:55:56Z

1

A file name isn't surrounded by quotes. You just use those when calling out a file from the command prompt to escape and spaces in the filename.

So take the quote out of the macro:

#define FILENAME(path, f_)  path f_
...
printf("\n%s", FILENAME(PATH, F_PWD));

answered Nov 11, 2021 at 2:55

dbush

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1 Comment

Anil Over a year ago

Indeed. Removing quotes did the trick. Thank you.

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