C name a file the date

Question

First off all: I know, some similar problems have been there before, but it does not work for me.

I need to create a .txt file in C which is called "year/month/day_hour :minute

My code is:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
int main(){
int hours, minutes, seconds, day, month, year;
char fileSpec [255];
//TIME for file name
    time_t now;
    time(&now);
    printf("Today is : %s", ctime(&now));
    struct tm *local = localtime(&now);
 
    hours = local->tm_hour;          
    minutes = local->tm_min;         
    seconds = local->tm_sec;         
 
    day = local->tm_mday;            
    month = local->tm_mon + 1;       
    year = local->tm_year + 1900;   
      
    //Time block end

    //create file
    FILE * fPointer;
    snprintf( fileSpec, "%04d_%02d_%02d_%02d:%02d.txt",year,month,day,hours,minutes); //From another post. I do not exactly know the syntax
    fPointer = fopen(fileSpec,"w");
    fprintf(fPointer ,"Date and Time of creation: %d/%d/%d %d:%d:%d\n",day,month,year,hours,minutes,seconds);
}

Sry for my strange formatting :/

I am still quite a beginner.

Edit: The whole code is: https://pastebin.com/78fSRJgx

You should state what your actual problem is. But I guess it stems from using / in a filename. That doesn't work as that separates directories. — koder, Jan 22 '21 at 09:31

score 1 · Answer 1 · answered Jan 22 '21 at 09:34

1

I had a similar issue one time on Android and I've spent hours trying to figure out the issue. It turns out it was my issue.

The problem is that you cannot use the '/' symbol for a file name, because that is known in the file system as the separator for directories. Thus, the filesystem might get stuck or might never find a file that has '/' in the name.

A comprehensive answer for this is this

answered Jan 22 '21 at 09:34

David Buzatu

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8
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What did you try? I was trying to say that you cannot have the symbol '/' in your filename. Maybe replace that with underscore `_` or something that can be used – David Buzatu Jan 22 '21 at 09:48
I did replace it with _, but still does not work. The newest version is at the pastebin – Ninto 1 Jan 22 '21 at 09:51
Are you using windows? – David Buzatu Jan 22 '21 at 09:56
If yes, follow the suggestions from this [post & answer](https://stackoverflow.com/a/10386576/11023871) – David Buzatu Jan 22 '21 at 09:57
Did not help -_-. I think, there are also other mistakes, but I can't identify them – Ninto 1 Jan 22 '21 at 10:13

score 1 · Accepted Answer · answered Jan 22 '21 at 10:54

The second argument in a call to snprintf should be max. buffer size, you didn't give that argument. Replacing

snprintf( fileSpec, "%04d_%02d_%02d_%02d:%02d.txt",year,month,day,hours,minutes);

with

snprintf( fileSpec, 255, "%04d_%02d_%02d_%02d:%02d.txt",year,month,day,hours,minutes);

(where 255 is the maximum length of the string snprintf will write) seems like it should solve your problem.

C name a file the date

2 Answers2