Naming files in c

[sandeep080]

Hi,

I'm student working on a project which requires me to create text files using C program. My problem is that i want to create say a 100 text files which has to be named in the following format: name001.txt , name002.txt , and so on till hundred..

I'm not finding a logic by which I can name theSE files in this way using loops..
I'm sure there is some way.. else we need to write 100 statements to open EACH file. eg:

FILE* fp[100];
fp[0]=fopen("name001","w");
fp[1]=fopen("name002","w");
.
.
.
till 100??

pls help???

Thanks

[EVOEx]

Why the double post? But yes, you should use a for loop for this.

[sandeep080]

*sorry for the double post.. i'm a first time user..

I need the logic of renaming the text file everytime the loop is executed?? how do you do this??

thanks

[grumpy]

Work out how to write an integer to a string and looping becomes easy. sprintf() supports relevant format specifiers.

[Adak]

See if this helps your thinking along:

You have a char fileName array. You declare it with the base name you want:

char fileName[] = {"name"};
char add[4] = {'\0'};

Then in your loop you use itoa to change your iterator, into a string, and assign it to "add[]".

Now strcat() add onto the end of fileName, and you can then open the file:

fp = fopen(fileName, "wt");

Just like normal, except don't put double quotation marks around fileName.

sprintf() is a good way also,

[sandeep080]

@Adak..

as per your reccomendation i tried this code(below).. but the program is running into an error state.. and a pop up appears saying, "... has encountered a problem and needs to close. We are sorry for the inconvenience".. i'm worried about the type conversion in add[0]=i;
anyway thanks again..

//file name numbering program
#include<stdio.h>
#include<string.h>
void main()
{
int i;
FILE* fp;
char fileName[]={"name"};
char add[4]={'\0'};
char s[]={"C PROGRAMMING"};//sample text that has to be written into the file
for(i=0;i<10;i++)
{
add[0]=i;//is type conversion needed here ie. add[0]=(char)i; ???
printf("%c",add[0]);
strcat(fileName,add); //concatenating to change file name everytime
fp=fopen(fileName,"wt");
fprintf(fp,"%s",s);
fclose(fp);
}
}

[tabstop]

If you define fileName as only being four characters long, you probably won't be able to add much to it. (That's a bug in Adak's original too, I'm afraid.) Your printf is just plain broken, though. You want to print to a string, which printf doesn't do.

[Adak]

You need to size fileName a bit bigger - my fault. Below is your program, with just a few tweaks.

@Adak..

as per your reccomendation i tried this code(below).. but the program is running into an error state.. and a pop up appears saying, "... has encountered a problem and needs to close. We are sorry for the inconvenience".. i'm worried about the type conversion in add[0]=i;
anyway thanks again..

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

//void main() let's use int main() instead!
int main()
{
    int i;
    FILE* fp;
    char fileName[8]={"name"};  //handles up to 3 numbers being appended
    char add[4]={'\0'};
    char s[]={"C PROGRAMMING"};//sample text that has to be written into the file

    printf("\n\n");
    for(i=0;i<10;i++)
    {
        add[0]= (char) (i + '0'); //type conversion can help, 
        printf("%c",add[0]);
        strcat(fileName,add); //concatenating to change file name everytime
        fp=fopen(fileName,"wt");
        fprintf(fp,"%s",s);
        fclose(fp);
        fileName[4] = '\0'; //resets fileName for the next number
    }

  printf("\n\n\t\t\t     press enter when ready");
  i = getchar();
  return 0;
}

You're welcome!

[EVOEx]

You need to size fileName a bit bigger - my fault. Below is your program, with just a few tweaks.

And yet, still, completely wrong :P.

Use sprintf.

[Adak]

And yet, still, completely wrong :P.

Use sprintf.

I have already posted that you can use sprintf() to do this. I just chose another way. The program as posted, creates 10 files with consecutively numbered filenames, and writes the string in each one of them.

That doesn't fit my definition of "wrong".

[Dino]

That doesn't fit my definition of "wrong".

This is true. hack != wrong.

[msh]

That's nice. But it will crash and burn if you go over 10 files.

[EVOEx]

I have already posted that you can use sprintf() to do this. I just chose another way. The program as posted, creates 10 files with consecutively numbered filenames, and writes the string in each one of them.

That doesn't fit my definition of "wrong".

Not in "wrong" as in that it doesn't work. But definitely, undoubtedly "wrong" as in that it's NOT the way to go.

[Adak]

Yes, it will go weird after 10 files, but that is all the OP put into his for loop, and this was the logic he chose.

I suggested using itoa(), but the OP wanted it that way.

    for(i=0;i<10;i++)
    {
        //add[0]= (char) (i + '0'); //type conversion can help, 
        itoa(i, add, 10);  
        printf("%c",add[0]);
        strcat(fileName,add); //concatenating to change file name everytime
        fp=fopen(fileName,"wt");
        fprintf(fp,"%s",s);
        fclose(fp);
        fileName[4] = '\0'; //resets fileName for the next number
    }

Sprintf() is a better choice, but itoa() was the first thing that came to my mind. I leave that wrinkle, as an exercise for the OP.

[Adak]

Not in "wrong" as in that it doesn't work. But definitely, undoubtedly "wrong" as in that it's NOT the way to go.

Probably why I didn't suggest the cast method, but the OP wanted it.

Nothing wrong with the OP experimenting and finding out some logic doesn't work, or works only in a limited range.