create unique file

[crescen7]

What I'm trying to do - if possible is open(create) a file using a dynamicly generated file name.



I"m working in a Linux environment using C



Currently the existing function is passed four variables from the main program, the function creates a message using the variables, then writes it to a file. One of the variables passed to the function is a "message ID" it would be perfect if I could find a way to name the file to be created with the messageID variable.



In theory Something like:

FILE *newfile;

newfile = fopen("%s",msgID, "w");



would be great, but of course fopen won't accept the additional argument so that won't work.



In any case, if I could just create a new unique file for each instance I could work around it not having the exact message ID as it's name.



Any ideas would be appreciated.



rm

[Salem]

Use sprintf to create whatever name you like, in whatever format you like, then open that

char fname[100];
sprintf( fname, ....
fp = fopen( fname, ...

[crescen7]

Originally posted by Salem
Use sprintf to create whatever name you like, in whatever format you like, then open that



char fname[100];

sprintf( fname, ....

fp = fopen( fname, ...

Either I'm misunderstanding (quite possible) or this doesn't do what I want.
I understand that I can create whatever file name I want and open it, but I would like a new file name created at every time the function is called.

The function looks like this:

int bounce(char *Uname, char *Udomain, char *Sname, char *msgID)
//the above variables are passed to the function from the main program

FILE = *newfile
newfile=fopen("bounce","w")'; //This creates a new file named bounce
//but it is overwritten when the next
//variables are passed.
//the function continues with:
fprintf(newfile,"Bla Bla%sbla bla%s bla%s",Uname, Udoman.....);
fclose(newfile);

The idea is to have a new file created, ideally using the *msgID variable as the file name, thereby generating a new file with each instance.

The problem is that fopen won't accept a variable argument for the file name - only a constant within the " ..". Also it won't accept a variable without giving a warning and then dumping core if I try to run it.

Again, I could be missing something - I'm very new at this - type slowly!

thanks

rm

[Salem]

Given that msgID is already a char*, I'm guessing it is also a string (one containing printable chars, ending in \0 )

If this is so, then it's dead easy

FILE *newfile;
newfile=fopen(msgID,"w");

[crescen7]

Originally posted by Salem
Given that msgID is already a char*, I'm guessing it is also a string (one containing printable chars, ending in \0 )



If this is so, then it's dead easy



FILE *newfile;

newfile=fopen(msgID,"w");

Hey, thanks for the quick reply....

You guessed right it is a string with printable characters ending in \0

but when I use:
FILE *newfile;
newfile=fopen(msgID,"w"); [/B][/QUOTE]

The compiler warns:: Dammit

Forget all that , the compiler warning was about a mistake in my fprintf statement. Damn - I was sure I tried it this way berfore!

Thanks it works great.!

[quzah]

#include <stdio.h>
int main( void )
{
    char buf[80]={0};
    FILE *fp = NULL;

    printf("Enter a  name: ");
    fscanf( buf, 80, stdin );

    fp = fopen( buf, "w" );
    fputs( buf, fp );
    fclose( fp );

     return 0;
}

Now then, assuming you enter a valid name, this program will open a file for writing with the name you provide, and write that name to the file, then it will close the file.

Do you understand now?

Quzah.