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turning userinput into a text file

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Join Date: Jan 2007

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cusado

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turning userinput into a text file

Feb 12th, 2007

how to turn a user input into a text file for example user inputs 100 and the program creates a text file named 100.txt?
I have tried to work it out but it still doesnt work properly.
i used

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
getc(stdin);  
 
char filename[80];
sprintf(filename,"%d.txt", stdin);
getc(stdin);  

char filename[80];
sprintf(filename,"%d.txt", stdin);

and then i also tried

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
char line[255];
fgets(line, 255, stdin);
 
char filename[80];
sprintf(filename,"%d.txt", stdin);
char line[255];
fgets(line, 255, stdin);
   
char filename[80];
sprintf(filename,"%d.txt", stdin);

any ideas on why it wont create the text file?

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John A

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Re: turning userinput into a text file

Feb 12th, 2007

This line is incorrect:

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sprintf(filename,"%d.txt", stdin);

Since you've already gotten the input from stdin, you should be supplying the variable which contains the user input as an argument instead of stdin.

And since you read it in as a string, you'll want to change "%d" to "%s". Also beware of newlines in your string, which could thoroughly mess up your program.

"Technological progress is like an axe in the hands of a pathological criminal."

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cusado

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Re: turning userinput into a text file

Feb 13th, 2007

the program runs, but no output file is generated? am i missing a command still?

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
char line[255];
fgets(line, 255, stdin);
char filename[80];
sprintf(filename,"%s.txt",line);
char line[255];
fgets(line, 255, stdin);
char filename[80];
sprintf(filename,"%s.txt",line);

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John A

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Re: turning userinput into a text file

Feb 13th, 2007

Read my last sentance:

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Originally Posted by Me

Also beware of newlines in your string, which could thoroughly mess up your program.

You're going to have to remove the newline character (if it's there), which is usually as simple as doing the following

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 C Syntax (Toggle Plain Text) 
if (string[strlen(string)-1] == '\n')
   string[strlen(string)-1] = '\0';
if (string[strlen(string)-1] == '\n')
   string[strlen(string)-1] = '\0';

Anyhow, the code works fine for me, even without the newline character removal. So perhaps it would be best for you to show us the code you're using?

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cusado

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Re: turning userinput into a text file

Feb 13th, 2007

well the entirety is only

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main(int argc, char *argv[]) {
char line[255];
fgets(line, 255, stdin);
char filename[80];
sprintf(filename,"%s.txt",line);
  return 0;
}
#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main(int argc, char *argv[]) {
char line[255];
fgets(line, 255, stdin);
char filename[80];
sprintf(filename,"%s.txt",line);
  return 0;
}

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WaltP

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Re: turning userinput into a text file

Feb 13th, 2007

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Originally Posted by cusado

the program runs, but no output file is generated? am i missing a command still?
Help with Code Tags

c Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main(int argc, char *argv[]) {
char line[255];
fgets(line, 255, stdin);
char filename[80];      // This line can't be here.  It has to 
                        // be above all executable code in C
sprintf(filename,"%s.txt",line);
  return 0;
}
#include <stdio.h> #include <string.h> #include <ctype.h> int main(int argc, char *argv[]) { char line[255]; fgets(line, 255, stdin); char filename[80]; // This line can't be here. It has to // be above all executable code in C sprintf(filename,"%s.txt",line); return 0; }

Yeah. Where do you:
1) open the file after you generate the name?
2) write to the file?
3) close the file before exiting?

The 3 Laws of the Procrastination Society:
1) Never do today that which can be put off until tomorrow
2) Tomorrow never comes

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cusado

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Re: turning userinput into a text file

Feb 13th, 2007

well all i want to do is for the user to input a name or number and for the program to create a text file with that name. im not actually writing anything into the file, its just an empty .txt file with a name that hte user chose

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WaltP

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Re: turning userinput into a text file

Feb 13th, 2007

You still have to open the file for writing. It doesn't magically get created just because you create a name in a variable...

Look up fopen()

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1) Never do today that which can be put off until tomorrow
2) Tomorrow never comes

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cusado

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Re: turning userinput into a text file

Feb 13th, 2007

well i used

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
fout = fopen("%s.txt", "w");
fout = fopen("%s.txt", "w");

but how do i represet "%s.txt" as the user's input?

Last edited by Ancient Dragon; Feb 13th, 2007 at 6:08 pm. Reason: removed ugly colors and added code tags

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Re: turning userinput into a text file

#10

Feb 13th, 2007

•

Originally Posted by cusado

well i used

fout = fopen("%s.txt", "w");

but how do i represet "%s.txt" as the user's input?

you already posted the answer to that question in your post #5. Just use variable filename

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
sprintf(filename,"%s.txt",line); // <<< from your previous post
fout = fopen(filename, "w");
sprintf(filename,"%s.txt",line); // <<< from your previous post
fout = fopen(filename, "w");