#FILE handling

29 messages · Page 1 of 1 (latest)

turbid spire
# 
#include <stdio.h>

int main()
{    
    // Opens file, if file does not exist, create it. Position at end
    FILE *pF = fopen("runcount.txt", "r+");
    if (pF == NULL)
    {
        fprintf(pF, "run #1\n");
        fclose(pF);
    }
    else
    {
        char runcounter[100];
        fscanf(pF, "%s", runcounter);
        int count = runcounter[6];
        count = count + 1;
        runcounter[6] = count;
        fprintf(pF, "%s", runcounter);
        printf("%s", runcounter);
    }
    
    return 0;
}```
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jolly dockBOT
#

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turbid spire
#

I'm trying to make a run counter which replaces the contents of a .txt file with +1 each time it's run

#

and also print it to the terminal

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any ideas where i might hav egone wrong?

# 
  if (feof(pF) == 0)
#

I also tried that

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How do i check if a file is empty?

twilit copper
# turbid spire ```c #include <stdio.h> int main() { // Opens file, if file does not ex...

// Opens file, if file does not exist, create it. Position at end

"r+"

Opens a file to update both reading and writing. The file must exist.
https://www.tutorialspoint.com/c_standard_library/c_function_fopen.htm

C library function - fopen()

C library function fopen() - The C library function FILE *fopen(const char *filename, const char *mode) opens the filename pointed to, by filename using the given mode.

turbid spire
#

Yes but if it doesn't exist, i want to create it

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so i can't use r+

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There are two cases

  1. If it doesn't exist, create it and add the text
  2. If it exists, replace 1 integer from it
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So open it with w for 1.

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and r+ for 2

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Since none applies, i went with a+

twilit copper
turbid spire
#

That is wrong..

#

that only checks if the file exists or not.

twilit copper
#

What ? look at the answers not the question

twilit copper
# turbid spire that only checks if the file exists or not.

you can do this

FILE *pF = fopen("runcount.txt", "a+");
if (pF != NULL) {
  fseek(pF, 0, SEEK_END);
  int size = ftell(pF);

  if (0 == size) {
  }
}

WIth a+ like you said to create if it doesn't exist, then check if properly open, then check if size is 0 (empty)

turbid spire
#

Lovely i got it to work

#

now i just have problem replacing the number

# 
#include <stdio.h>

int main()
{
    // Opens file, if file does not exist, create it. Position at end
    FILE *pF = fopen("runcount.txt", "a+");

    fseek(pF, 0, SEEK_END);
    long size = ftell(pF);

    if (0 == size)
    {
        rewind(pF);
        fprintf(pF, "run #1\n");
        printf("run #1\n");
    }
    else
    {
        int runcounter;
        fscanf(pF, "run #%d", runcounter);
        runcounter = runcounter + 1;
        freopen("runcount.txt", "w", pF);
        fprintf(pF, "run #%d", runcounter);
    }

    fclose(pF);
    return 0;
}
#

For the love of god please someone

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;-;

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Why isn't it replacing the number?

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and incrementing it

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in my else

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!solved