Thread: Read tab delimited file with selected output

Hi,

I'm new to C programming. I have a question and I'm stuck for weeks. I have a file (example: abc.txt) with the following values, tab delimited:

a1 \t b4 \t c5 \t 1
a5 \t b1 \t c3 \t 1
a6 \t b2 \t c4 \t 1
a2 \t b3 \t c7 \t 2
a1 \t b4 \t c5 \t 2
a5 \t b1 \t c3 \t 2
a6 \t b2 \t c4 \t 3
a2 \t b3 \t c7 \t 3
a2 \t b3 \t c7 \t 3

And I want only the selected column 4 with the number 2 data to pull out to a new file lets say def.txt, and the data will look like this:

a2 \t 2
a1 \t 2
a5 \t 2

How can I achieve doing that? I'm using C, my head is like gonna explode looking at it. Here's my code:

Code:

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


int main(void)
{


   static const char filename[] = "abc.txt";
   FILE *file = fopen(filename, "r");


   if ( file != NULL )
   {
      char line[BUFSIZ];


	  char col1[BUFSIZ], col2[BUFSIZ], col3[BUFSIZE];
	  int col4[BUFSIZ];


      while ( fgets(line, sizeof line, file) != NULL )
      {
         if ( sscanf(line, "%s %s %s %s", col1, col2, col3, &col4) == 4 )
           {
			   if (col4 == 2)
			   {
			     printf("%s\t%s\n", col1, col4);
			   }
           }


	  } 
	  system("pause");
   }
   else
   {
      perror(filename);
   }
   return 0;
}

I haven't write the write on new file part, still stuck on sorting out the data part. Need advice and thank you in advance!

So is there a problem with your code? Does this code compile without errors or warnings? If not post the entire error/warning messages, exactly as they appear in your development environment.

Jim

scanf with a %s will consume both the alpha character and the number. your scanf needs to be more granular. and col4 doesn't need to be an array if it is a single number

Code:

int main()
{
        const char *s = "a1\tb2\tc3\td4";
        char a;
        char b;
        char c;
        char d;
        int  i;
        int  j;
        int  k;
        int  l;
        sscanf(s,"%c%d %c%d %c%d %c%d",&a,&i,&b,&j,&c,&k,&d,&l);
        printf("%c\n",a);
        printf("%d\n",i);
        printf("%c\n",b);
        printf("%d\n",j);
        printf("%c\n",c);
        printf("%d\n",k);
        printf("%c\n",d);
        printf("%d\n",l);
    return 0;
}

this only works if you only have a single character then a number. the number can be more than 1 character long.