Question

I have the following data file

1.0
2.0
3.0 

This is an a file text.dat. The following code I have so far is in mygetline.c and I compile it into the executable mygetline. Executing it I feed the data file into the executable thus
./mygetline < text.dat in the bash terminal.

I want to read in the data file like that and print to stdout that column, plus some function of it. Here is the code so far.

#include <stdio.h>
int mygetline ( char s[], int lim )
{
  int c, i;

  i = 0;
  while( --lim > 0 && ( c = getchar() ) != EOF && c != '\n' )
  s[i++] = c;
  if ( c == '\n' )
  s[i++] = c;
  s[i] = '\0';
  return i ;
 }

void main()
{
     const int maxline = 10000;
     int nl, length;
     char line[maxline];
     double value ; 
     nl = 0;
     while ( ( length = mygetline( line, maxline ) ) != 0 ) //avoiding blanks
          {
    //Original error  sscanf( "%lf", line, &value ) ; //trying to get each line   
                                               //as the right 
                                              //number
       //FOllowing line is corrected implementation of sscanf()
              sscanf( line, "%lf", &value ) ; 
              printf( "%lf %lf\n", value ,value*value ) ; //trying to output x & x*x
           }
 }

the output is the following

0.000000 0.000000
0.000000 0.000000
0.000000 0.000000

I want something like

1.0 1.0 
2.0 4.0 
3.0 9.0

to whatever precision.
Does anyone have any suggestion as to what I am missing to get my desired output? Thank you

Answer 1

Re-read the documentation for sscanf.

The format is the second parameter.
But you put the "%lf" as the first parameter.