Write to a file the first word in each line from another file

[riahc3]

Hey

I have a file named filetext.txt with the text:

One word
Two words
Three words
Four words

and the program should read this filetext.txt and output to another file called filecopied.txt this text:

One
Two
Three
Four

I have this so far:

#include <assert.h>
#include <complex.h>
#include <ctype.h>
#include <errno.h>
#include <fenv.h>
#include <float.h>
#include <inttypes.h>
#include <iso646.h>
#include <limits.h>
#include <locale.h>
#include <math.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <wchar.h>
#include <wctype.h>



int main()
{
    FILE *filetext
    FILE *filecopied;
    char text[50];

    filetext=fopen("filetext.txt","r");
    filecopied=fopen("filecopied.txt","w");

    if ((filetext==NULL) || (filecopied==NULL))
        {
            printf ("A file cannot be opened");
            return 1;
        }

       // fgets(text,50,filetext);
        //sscanf("%s ",text);
        sscanf("%s\n",fgets(text,50,filetext));
        //sscanf("%s\n",fgets(text,50,filetext));
        fprintf(filecopied,"%s",text);
        fclose(filecopied);
        fclose(filetext);
        return 0;
}

It doesnt write anything to the file so how can I solve it? Id like to use fgets, fprintf, and sscanf. Thanks.

[Dave Sinkula]

int main()
{
   FILE *filetext;
   FILE *filecopied;
   char text[50];

   filetext=fopen("filetext.txt","r");
   filecopied=fopen("filecopied.txt","w");

   if ( (filetext==NULL) || (filecopied==NULL) )
   {
      printf ("A file cannot be opened");
      return 1;
   }

   while ( fgets(text, sizeof text, filetext) )
   {
      char first[10];
      if ( sscanf(text, "%9s", first) == 1 )
      {
         fprintf(filecopied, "%s\n", first);
      }
   }
   fclose(filecopied);
   fclose(filetext);
   return 0;
}

[Tom Gunn]

#include <assert.h>
#include <complex.h>
#include <ctype.h>
#include <errno.h>
#include <fenv.h>
#include <float.h>
#include <inttypes.h>
#include <iso646.h>
#include <limits.h>
#include <locale.h>
#include <math.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <wchar.h>
#include <wctype.h>

It is always good to learn which headers contain which declarations. Including everything under the sun when you use only a small fraction of it is rarely a good idea.

It doesnt write anything to the file so how can I solve it?

Double check the way sscanf() is supposed to be called. What you want are two strings, one for input and one for output:

char line[512];
char word[512];

while (fgets(line, sizeof line, filetext))
{
    if (sscanf(line, "%511s", word) == 1)
    {
        fprintf(filecopied, "%s\n", word);
    }
}

[riahc3]

I think both of you just limit in another array the amount of chars in a char array when I want it to read/write the first letters then when it detects the first space (" ") and when it detects a "\0", it should just to the next line again the first space and again a "\0" until it reaches EOF...

[riahc3]

Maybe I didnt understand someone correctly...

[Tom Gunn]

Id like to use fgets, fprintf, and sscanf.

I want it to read/write the first letters then when it detects the first space (" ") and when it detects a "\0", it should just to the next line again the first space and again a "\0" until it reaches EOF

These wants do not jive. If you use fgets() alone, you have no choice but to provide a buffer large enough to hold the maximum expected line length. If you use sscanf() to extract a word, you have no choice but to provide a buffer large enough to hold the maximum expected line length because the whole line could be one big word.

You can skip using sscanf() entirely by searching for the first whitespace in the line and save the memory for the second buffer:

char line[512];

while (fgets(line, sizeof line, filetext))
{
    size_t x = 0;

    while (line[x] && !isspace(line[x])) putc(line[x], filecopied);

    putc('\n', filecopied);
}

The algorithm from the second quote is a viable option, but I would need some convincing to believe that it is a better option than fgets() and sscanf(). Right now I am not sure what it is you want. Dave and I have both given you solutions that match your functional requirement of saving the first word in each line.