Automatically generate file names

[Freddy]

Hi all,

I use a C program to generate lots of data while changing many
parameters sometimes.

However, I am trying to find a way to let C generate the output file
names dependent on a few parameters that I keep changing. this way it
saves the pain of having to back up the output file and rename it
before running the program again.

I don't know if there is a solution for that.


Freddy

 

[Clever Monkey]

I use a C program to generate lots of data while changing many
parameters sometimes.

However, I am trying to find a way to let C generate the output file
names dependent on a few parameters that I keep changing. this way it
saves the pain of having to back up the output file and rename it
before running the program again.

I don't know if there is a solution for that.

tmpnam() may get you pretty close. You could munge the results to
retain uniqueness while providing dependencies upon your naming scheme.

 

[Mike Wahler]

Hi all,

I use a C program to generate lots of data while changing many
parameters sometimes.

However, I am trying to find a way to let C generate the output file
names dependent on a few parameters that I keep changing. this way it
saves the pain of having to back up the output file and rename it
before running the program again.

I don't know if there is a solution for that.

Here's a simple function that creates a file
name which uses the parameter 'num':

#include <stdio.h>
#define FN_MAX_LEN 128 /* you need to determine best value for this */

const char *filename(unsigned int num)
{
static char filename[FN_MAX_LEN];
sprintf(filename, "%s%d", "file", num);
return filename;
}

int main()
{
unsigned int i = 0;
for(i = 1; i <= 5; ++i)
{
const char *fn = filename(i);
puts(fn);
}

return 0;
}

Output:

file1
file2
file3
file4
file5


-Mike

 

[Malcolm McLean]

Hi all,

I use a C program to generate lots of data while changing many
parameters sometimes.

However, I am trying to find a way to let C generate the output file
names dependent on a few parameters that I keep changing. this way it
saves the pain of having to back up the output file and rename it
before running the program again.

I don't know if there is a solution for that.

sprintf(path, "myfile%sversion%galgo%s.freddy\n", programname, version,
algorithmname);

fp = fopen(path, "w");

 

[Jack Klein]

Here's a simple function that creates a file
name which uses the parameter 'num':

#include <stdio.h>
#define FN_MAX_LEN 128 /* you need to determine best value for this */

[snip]

If you use the standard macro FILENAME_MAX from the already-included
<stdio.h>, the determination is done for you.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
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alt.comp.lang.learn.c-c++
http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html

 

[Mike Wahler]

On Mon, 26 Mar 2007 18:14:52 GMT, "Mike Wahler"

#include <stdio.h>
#define FN_MAX_LEN 128 /* you need to determine best value for this */

[snip]

If you use the standard macro FILENAME_MAX from the already-included
<stdio.h>, the determination is done for you.

I always seem to forget about that one. Thanks.

-Mike

 

[Keith Thompson]

On Mon, 26 Mar 2007 18:14:52 GMT, "Mike Wahler"

#include <stdio.h>
#define FN_MAX_LEN 128 /* you need to determine best value for this */

[snip]

If you use the standard macro FILENAME_MAX from the already-included
<stdio.h>, the determination is done for you.

I always seem to forget about that one. Thanks.

FILENAME_MAX is not necessarily as meaningful as you might expect it
to be. The standard says it:

expands to an integer constant expression that is the size needed
for an array of char large enough to hold the longest file name
string that the implementation guarantees can be opened

with a footnote:

If the implementation imposes no practical limit on the length of
file name strings, the value of FILENAME_MAX should instead be the
recommended size of an array intended to hold a file name
string. Of course, file name string contents are subject to other
system-specific constraints; therefore all possible strings of
length FILENAME_MAX cannot be expected to be opened successfully.