Help creating multiple text files

Hello all,

I was trying to practice moving my programs into functions, so they are not only in the main() and also with creating files.

I can create a single file with no problem. However, I could not get my program to succeed with creating multiple files.

I want the program to be able to create say 4 text files each with a unique name and be concatenated with .txt at the end:

text1.txt
..
text4.txt

Could someone point out where I am going wrong please?

Here is the code I have done:

Code:

---


#include<stdio.h>

int file_generator(int number);


main()
{

int nrfiles = 4;


file_generator(nrfiles);

}


int file_generator(int number)
{

FILE  *nf;
int i=1;
char newfile[10];
for(i;i<=number;i++)
{

newfile[i] = "test";

nf = fopen(newfile[i], "w");

if (nf == NULL) {
  fprintf(stderr, "Can't open created file %s!\n",
          newfile);
  exit(1);
}
fclose(nf);
}
}

---

Perhaps you want to look at using sprintf() to combine strings with numbers?

--
Mats

i am upset now.

I ammended the above program

so that"

Code:

---

nf = fopen(newfile[i], "w");

---

is just:

Code:

---

nf = fopen(newfile, "w");

---

I compiled and ran the program and it produced this output files:

Code:

---

?0?????[?  ?0000??[?  000q?????  array    atm.c  file    matrix    test.txt
?00????[?  0000?????  00?q?????  array.c  conv    file.c  matrix.c
?000???[?  00000????  0??q?????

---

i ran rm ?*

and all my files were deleted
:-(

Sorry to hear that.

In unix (and Windows too) ? means "any character", and "*" means "any number of any character".

Perhaps before you start creating files, just print the name you come up with?

--
Mats

thanks matsp, I am trying that now. I mean to print out the names first.

I managed to get the function to print out a diffierent name by using an array.

I just cannot get the function to use this name now to create the file:

Code:

---

int file_generator(int number)
{       
char ch = 'a';
FILE  *nf;
int i=0;
char newfile[number];

for(i;i<=number;i++)
  { 
  newfile[i] = ch;
  printf("%c\n", newfile[i]);
   
   
  nf = fopen(newfile[i], "w");
  if (nf == NULL) {
  fprintf(stderr, "Can't open created file %s!\n",
          newfile);
  exit(1);
  }
   
  if (nf == NULL) {
  fclose(nf);
  }
  ch = ch++;
  }

---

I kind of solved this with :

Code:

---

int file_generator(int number)
{       
char ch = 'a';
FILE  *nf;
int i=0;
char newfile[number];

for(i;i<=number;i++)
  { 
  newfile[i] = ch ;
  printf("%c\n", newfile[i]);
   
  nf = fopen(newfile, "w");
  if (nf == NULL) {
  fprintf(stderr, "Can't open created file %s!\n",
          newfile[i]);
  exit(1);
  }
   
  if (nf == NULL) {
  fclose(nf);
  }

  ch = ch++;
  }
}

---

but it creates files like this:

Code:

---

:~/Programming$ ls
a  ab  abc  abcd  abcde  file  file.c

---

i am tired so I will go to bed

Ok, first some petty details:
Your string is too short. If you use i <= number, you will need to have a array that is number+2 characters long.

Code:

---

ch = ch++;

---

Just ch++ is fine - it does what you need. The "ch =" part is completely unnecessary.

Code:

---

  if (nf == NULL) {
  fclose(nf);
  }

---

Would it not be a better idea to close the file if it WAS success?

Now, what do you actually want to do? Just create files called a, b, c, d, e? If so, you need to set the FIRST character of your array to whatever you want to call the file, and the second entry to 0. That way, you have a string of 1 character. You are currently setting position "i" in the array to the letter - that is not right.

--
Mats

Quote:

---

i am tired so I will go to bed

---

Hey, sleepy head :)

Code:

---

#include <stdio.h>

void filenumber(void);

int main(void)  {
  int i;

  printf("\n\n Our Files Are: \n");
  for(i = 0; i < 2; i++)
      filenumber();


  printf("\n\n\t\t\t    press enter when ready ");
  i = getchar();
  return 0;
}
void filenumber(void) 
{       
  FILE  *nf;
  char filename[10] = {"Text"};
  char ext[5] = {".txt"}
  char afilenumber[3] = {'\0'};
  int i=0, j;

  static int filenumber = 0;

  for(i = 0; i < 4; i++)  {
      filenumber++;   
      itoa(filenumber, afilenumber, 10);
      strcat(filename, afilenumber);
      strcat(filename, ext);
 
      if((nf = fopen(filename, "w")) == NULL)  {
        fprintf(stderr, "Can't open %s file!\n", filename);
        exit(1);
      }
     
      printf("\t The new file name is %s \n", filename);
     
      filename[4] = '\0';
      fclose(nf);
  }
  return 0;
}

---

Edit: changed to make text1.txt, text2.txt, text3.txt, etc., filenames (but I haven't tried this out yet :) ).

Thanks matsp for you valuable input. And Adak, what a nice surprise to see your effort!

I will have to wait till this evening to try these. Will let you both know what happens.

Again, much thanks both of you.

Hello there. I tried to do as you said matsp but I didn't manage. I am not sure how to do what you say:

Code:

---

you need to set the FIRST character of your array to whatever you want to call the file, and the second entry to 0. That way, you have a string of 1 character. You are currently setting position "i" in the array to the letter - that is not right.

---

I tried to do it a different way using pointers, but I get the same result:

Code:

---

int file_generator(int number)
{

char newfile[6] = {"TomB"};

char ch = 'a';
char *nfP;
nfP = &newfile;

FILE  *nf;
int i=0;

for(i;i<=number;i++)
  {
  printf("%c\n", *nfP);

  nf = fopen(nfP, "w");
  nfP++;
    if (nf == NULL) {
    fprintf(stderr, "Can't open created file %s!\n",
          nfP);
  exit(1);
  }

  if (nf == NULL) {
  fclose(nf);
  }
  }
}

---

which yields:

Code:

---

B  file  file.c  mB  omB  TomB

---

I feel like I am digging my own TomB here!

What file names are you trying to create?

I changed my program to make text1.txt, text2.txt, etc., filenames (untested for that part, however).

For the above program that I did to just take the array contents "TomB" and create from it files:

T
o
m
B

instead of the result stated above. I couldn't solve it :-(
I think it is slightly too much for me at this limited stage in my C experience.

Let me mess wit it - wit a hammer, if necessary! :)

Code:

---


#include <stdio.h>

int main()  {
  int i;
  char newfile[6] = {"TomB"};
  char *ch;

  FILE  *nf;

  i = 0;
  while(newfile[i]) {
      ch = &newfile[i];
      nf = fopen(ch, "w");

      printf("\n%c ", *ch);
      i++;
      if (nf == NULL) {
        fprintf(stderr, "Can't open created file %c!\n", ch);
        exit(1);
      }
  //if nf == NULL the file was never opened, so no need to close it :)
  }
  i = getchar();
  return 0;
}

---

Try that.

Thanks adak, but it gives the same result as my effort previously. Is very frustrating. Yours does look nicer though!

I will muck around with your version now. maybe I missed something.

OK, one more time! :)

Code:

---

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

int main()  {
  char ch;
  char file[12] = {"TomB"};
  char newfile[12] = {"\0"};
  char ext[5] = {".txt"};
  int i = 0, length, j;
  FILE  *nf;
 
  printf("\n\n"); 
  while(ch = file[i]) {
      newfile[0] = ch;
      strcat(newfile, ext);
      nf = fopen(newfile, "w");

      printf("\n%s ", newfile);
      if (nf == NULL) {
        fprintf(stderr, "Can't open created file %s!\n", newfile);
        exit(1);
      }
      length = strlen(newfile);
      for(j = 0; j < length; j++)
        newfile[j] = '\0';
      ++i;

  }
  j = getchar();
  return 0;
}

---

Output:

T.txt
o.txt
m.txt
B.txt

using strcat when you need to update only 1 char... too complicated

Code:

---

char mask[] = "TomB";
char name[] = "1.txt";
size_t len = strlen(mask);
size_t i;
for(i = 0; i< len; i++)
{
  FILE* fp;
  name[0] = mask[i]; /* see - you just replace 1 char in the name */
  fp = fopen (name, "w");
  if(fp)
  {
      printf("File %s opened\n", name);
      fclose(fp);
  }
}

---

something like that should work I suppose

Why not put the filename generating code into its own function, to simplify things?

Code:

---

char* generate_filename( const char* template_name, int index, const char* extension, char* buffer, int maxlen )
{
        char digits[ 32 ];
        sprintf( digits, "%d", index );
        if( ( int )( strlen( template_name ) + strlen( digits ) + strlen( extension ) + 1 ) > maxlen )
                return NULL;
        strcpy( buffer, template_name );
        strcat( buffer, digits );
        strcat( buffer, extension );
        return buffer;
}

int main( void )
{
        char buffer[ 1024 ];
        for( int i = 12; i < 20; i++ )
        {
                if( generate_filename( "TomB", i, ".txt", buffer, 1024 ) )
                {
                        puts( buffer );
                }
                else
                {
                        puts( "buffer too small" );
                }
        }
}

---

Thank you all for your input, it has given me a lot to think about and to learn. I will try to understand fully what you have all shown.

I will not look into how to consolidate all this and to learn how to actually manipulate the files now.

Thanks again!

:)