reading values from a file

**megastar** · 06-24-2007

There is a file which has data in the way shown below.
Each row is sort of a record.
For each record i will be needing values in the first column(+/- 1) and the other floating
point values in the row
eg:.23232
(not the colon':' and the serial numbers)
(The number of fields is same in each row)
The source is in c.The way i had in mind was using a structure
with int char double fields and then using fscanf to read them as it is
and then extracting the requisite values.
The problem is since the data in all rows may not be spaced uniformly in
all rows(not a possibility but since data is huge cannot be predicted)
it is becoming difficult to move the file pointer in same way in all rows.
Can someone suggest a simple and computationally inexpensive way of
storing the values?

FILE

Code:

1 1:.2345 2:.3454 3:.238909  ........            10,000:.4329407
-1 1:.1201890 2:.121211 .............               10,000:.3123123
-1 1:.12323 2:.312312.......                                10,000:.312081290
.
.
.
.
.
-1  1:.3213123 2:.321312                                     10,000:.31231232

**Salem** · 06-24-2007

Are you suggesting that you have up to 10000 id:value pairs on each row of the table?

Do the id parts really have comma in the thousands ?

**megastar** · 06-24-2007

The number of entries depends on the file(usually of the order thousands)
but the essential format is the same.
Thus the id:value pairs are in thousands.
Sorry about the comma part, there are no commas in the thousands,
thanks for pointing out.
Also the total number of rows generally does not exceed 100.

**Salem** · 06-25-2007

Try this

Code:

#include<stdio.h>
int main ( ) {
    FILE   *fp;

    fp = fopen("foo.txt","r");
    while ( 1 ) {
        int     id, result;
        double  val;
        result = fscanf( fp, "%d:%lf", &id, &val );
        if ( result == 1 ) {
            printf("ID: ID=%d\n", id );
        } else
        if ( result == 2 ) {
            printf("Pair: Value=%f\n", val );
        } else {
            /* almost certainly EOF, but in any case we're done */
            break;
        }
    }
    fclose(fp);    

	return 0;
}

$ cat foo.txt && ./a.exe
1 1:.2345 2:.3454 3:.238909 10000:.4329407
-1 1:.1201890 2:.121211 10000:.3123123

ID: ID=1
Pair: Value=0.234500
Pair: Value=0.345400
Pair: Value=0.238909
Pair: Value=0.432941
ID: ID=-1
Pair: Value=0.120189
Pair: Value=0.121211
Pair: Value=0.312312

**megastar** · 06-25-2007

Thanks !!
That was clever.. using fscanf's return value(did'nt remember [

]).
It is working.

Thread: reading values from a file

Thread Tools

Search Thread

Display

reading values from a file

Similar Threads

reading in a text file containing hex values

Dikumud

Simple File encryption

Unknown Memory Leak in Init() Function

what does this mean to you?