How to use simple file input and output in C

Question

Can someone please tell me how basic file input and output is supposed to be performed in C. I tried searching but I could get only solutions for C++ etc.

I am trying to use fscanf and fprintf to do this. However, the program crashes as soon as it executes this part with the error message saying: "Unhandled exception at 0x50D39686 (msvcr120d.dll) in Test Project.exe: 0xC0000005: Access violation writing location 0xCCCCCCCC." The file cats.txt is in location Documents\Visual Studio 2013\Projects\Test Project\Test Project My code is pasted below

#include <stdio.h>

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

int main()

{
    double things_in_file[6];
int counter;
FILE *file_cats;

if ((file_cats = fopen("cats.txt", "r")) == NULL)
{
    printf("This file doesn't exist.\n");
    system("pause");
    exit(-1);
}

for (counter = 0; counter <= 5; counter = counter + 1)
{

    fscanf(file_cats, "%lf\n", &things_in_file[counter]);
    printf("%f\n", things_in_file[counter]);

}

fclose("file_cats");
system("pause");

exit(0);

}

I figured out what was wrong. The line fclose("file_cats") should be fclose(file_cats). That fixes the issue for me.

counter <= 5 should be counter < 5 and fscanf ... &things_in_file[counter] — BLUEPIXY
– BLUEPIXY, Commented Dec 7, 2013 at 16:15
@BLUEPIXY - Your comment should be an answer. And tell the OP that he is overrunning the array buffer. — Steve Wellens
– Steve Wellens, Commented Dec 7, 2013 at 16:17
The fact that you program in MS VS 2013 is irrelevant for this question. Reading from files is standard and should work regardless of the IDE. — remus
– remus, Commented Dec 7, 2013 at 16:25
I just changed the dimension of the array from 5 to 6. But I still get this error message: "Unhandled exception at 0x50F79686 (msvcr120d.dll) in Test Project.exe: 0xC0000005: Access violation writing location 0xCCCCCCCC." — user3077855
– user3077855, Commented Dec 7, 2013 at 18:36
Sorry, I just noticed the comment pointning ou the missing "&" in fscanf function. I fixed that too. I do get the values from cat.txt listed in the black window, but I get this message soon after: "Unhandled exception at 0x50DC7EEB (msvcr120d.dll) in Test Project.exe: 0xC0000005: Access violation writing location 0x00EE58D8." — user3077855
– user3077855, Commented Dec 7, 2013 at 18:38

BLUEPIXY · Accepted Answer · 2013-12-07 16:21:36Z

1

array declaration eg array[5] is 5 element, index from 0 to 4 (0,1,2,3,4)

scanf requires the address of the variable to store the value

answered Dec 7, 2013 at 16:21

BLUEPIXY

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