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reading data from text file using fgets and sscanf

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Join Date: Jan 2009

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encee

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reading data from text file using fgets and sscanf

Jan 22nd, 2009

i am trying to read a text file like this and store each number as an integer (without the decimals) and print them

1 3 5.6 3 2.1 4
2 2 3 4.2 1

here is what i have now

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
#include <stdio.h>
#include <conio.h>
 
 
void main()
{
 int i, n=1;
 int n1=0,n2=0,n3=0,n4=0,n5=0,n6=0,n7=0,n8=0,n9=0,n10=0;
 char c[10];
 FILE *f1;
 f1=fopen("textfile.txt","r");
 while(fgets(c,10,f1)!=NULL)
 {
  sscanf(c,"%d %d %d %d %d %d %d %d %d %d", &n1, &n2, &n3, &n4, &n5, &n6, &n7, &n8, &n9, &n10);
  printf("%d %d %d %d %d %d %d %d %d %d\n",n1,n2,n3,n4,n5,n6,n7,n8,n9,n10);
  getch();
 }
#include <stdio.h>
#include <conio.h>


void main()
{
 int i, n=1;
 int n1=0,n2=0,n3=0,n4=0,n5=0,n6=0,n7=0,n8=0,n9=0,n10=0;
 char c[10];
 FILE *f1;
 f1=fopen("textfile.txt","r");
 while(fgets(c,10,f1)!=NULL)
 {
  sscanf(c,"%d %d %d %d %d %d %d %d %d %d", &n1, &n2, &n3, &n4, &n5, &n6, &n7, &n8, &n9, &n10);
  printf("%d %d %d %d %d %d %d %d %d %d\n",n1,n2,n3,n4,n5,n6,n7,n8,n9,n10);
  getch();
 }

but the output i get is always

1 3 5 0 0 0 0 0 0 0
2 2 3 4 0 0 0 0 0 0

its basically ignoring everything else once the sscanf encounters a decimal

Any suggestions??
Thanks

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Join Date: Dec 2005

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Salem

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Re: reading data from text file using fgets and sscanf

Jan 22nd, 2009

1. main returns int.
2. a 10 character buffer is nowhere near long enough to store 10 integers expressed as a string.

I would suggest
char c[BUFSIZ];
and update the fgets call accordingly.

Checking the return result of sscanf would be a good idea as well.

> its basically ignoring everything else once the sscanf encounters a decimal
Well what do you want to happen?
%d is for ints. If you want decimals, then use %f and adjust the data types.

Last edited by Salem; Jan 22nd, 2009 at 2:30 am.

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Join Date: Jan 2009

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encee

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Re: reading data from text file using fgets and sscanf

Jan 22nd, 2009

Thanks for the input.

•

Originally Posted by Salem

1. main returns int.
My bad, i almost alyways use int main

2. a 10 character buffer is nowhere near long enough to store 10 integers expressed as a string.

I've tried it with even a 100 character buffer with no difference in results. I will try BUFSIZ also..

I would suggest
char c[BUFSIZ];
and update the fgets call accordingly.

Checking the return result of sscanf would be a good idea as well.

> its basically ignoring everything else once the sscanf encounters a decimal
Well what do you want to happen?
%d is for ints. If you want decimals, then use %f and adjust the data types.

But if I assign a floating number as an integer, won't it implicitly convert it to int and move to the next character? However, it ignores ALL VALUES in that line of text after the decimal, which is what I find weird. I've also tried with floating point with no change in results...

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Join Date: May 2006

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WaltP

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Re: reading data from text file using fgets and sscanf

Jan 22nd, 2009

That's how sscanf works. A decimal is illegal for integers so the translation ends. You'll have to reconsider how you read/translate the file.

Also, consider these problems:

see this about void main()
You've defined c[] to be 10 characters. How many characters are in the first line for textfile.txt?

And see this about getch()

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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Join Date: Dec 2005

Posts: 5,850

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Salem

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Void main'ers are DOOMed

Re: reading data from text file using fgets and sscanf

Jan 22nd, 2009

Well if you want to ignore dots, then perhaps
"%d%*[^0-9]"
repeated 10 times

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me_ansh

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Re: reading data from text file using fgets and sscanf

Jan 22nd, 2009

Well, i think, this might be a simpler way to solve your problem. I took an array of inetegers to be populated.

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
int main(void)
{
     FILE *fp;
     char buff[100];
     int i = 0;
     int var[100];
 
     fp = fopen("./test.txt","r");
 
     while(fgets(buff,sizeof(buff),fp)
     {
          for(i=0;i<strlen(buff);i++)
          {
               if(isdigit(buff[i]))
               {
                    var[i] = buff[i] - 48;
                    printf("%d",var[i]);
                }
          }
     }
 
     printf("\n");
     return 0;
}
int main(void)
{
     FILE *fp;
     char buff[100];
     int i = 0;
     int var[100];
 
     fp = fopen("./test.txt","r");

     while(fgets(buff,sizeof(buff),fp)
     {
          for(i=0;i<strlen(buff);i++)
          {
               if(isdigit(buff[i]))
               {
                    var[i] = buff[i] - 48;
                    printf("%d",var[i]);
                }
          }
     }
     
     printf("\n");
     return 0;
}

Hope it helps you out..

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Rhohitman

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Re: reading data from text file using fgets and sscanf

Jan 23rd, 2009

try this out i will work i used fgetc, iguess you should know that its interger not some string to store in.

ASCII 48 = 0 and so on....

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
#include <iostream>
 
using namespace std;
#define size 10
 
int main()
{
     int no[size], temp=0, i;
 
     FILE *fp=fopen("textfile.txt","r");
     int ch=fgetc(fp);
     for(i=0; i<size; ch=fgetc(fp))
     {
             if(ch>='0' && ch<='9') //taking only no
                      temp=(temp*10)+(ch-48);
             else if(temp!=0)
             {
                 no[i]=temp;
                 printf("%d ", no[i]);
                 if(ch==EOF) break;
                 i++;
                 temp=0;
             }
     }
 
     system("pause");
     return 0;
}
#include <iostream>

using namespace std;
#define size 10

int main()
{
     int no[size], temp=0, i;
    
     FILE *fp=fopen("textfile.txt","r");
     int ch=fgetc(fp);
     for(i=0; i<size; ch=fgetc(fp))
     {
             if(ch>='0' && ch<='9') //taking only no
                      temp=(temp*10)+(ch-48);
             else if(temp!=0)
             {
                 no[i]=temp;
                 printf("%d ", no[i]);
                 if(ch==EOF) break;
                 i++;
                 temp=0;
             }
     }
     
     system("pause");
     return 0;
}