load multiple data into command line c

Question

Hi I have a c program that calculates a score (per person) based on 14 different parameters:

$ ./ScorecommandLine 30 0 0 0 0 0 35 1 1 1 130 1 1 1
0.057748

however at the moment I can only calculate one score at a time. What I would like to do is load the parameters multiple times for lots of different people i.e instead of doing:

$ ./ScorecommandLine 150 0 0 0 0 0 35 1 1 1 130 1 1 1
    0.0577487
$ ./ScorecommandLine 30 1 0 10 4 0 31 1 15 1 90 1 4 1
    0.0897333
$ ./ScorecommandLine 50 0 0 9 0 0 25 1 3 1 123 1 0 0
    0.4567748
$ ./ScorecommandLine 30 0 1 0 0 8 35 1 1 1 130 1 1 1
    0.0838395
$ ./ScorecommandLine 30 1 1 0 1 0 65 4 4 1 32 1 3 1
    0.0495855

where i have to run the command 5 times and have to type the new data for each person every time, I would rather have the data in a csv file and load that into the command line so my program returns all the scores in one go.

Answer 1

I suggest opening the file with fopen(), reading each line with fgets(), and then parsing out the numbers with sscanf().

Answer 2

Have your program read whole lines from stdin using fgets, say inside a while loop. Then use sscanf to parse the whole line into the variables your code needs. Still inside the while loop, run the bit that generates your score.

After you compile the program - pretend it is myprog:

myprog < myfile.csv

Answer 3

You have the right idea already! You're program is perfect, it only needs to be called N number of times to complete a job, and that can all be defined, as you say in a .csv file.

Now all you need is a program that reads a .csv file and calls your program N times to complete the job. A nice way to do this would be to use a separate c program and call your original program using popen. Even nicer still, as it's a small job, would be to write a shell script to do this for you.

Using something like popen is very simple, and exciting too; try The Art of Linux Programming to get an idea of how to start.

If you don't have time to learn popen, then you could always edit your original program. Just check if the first parameter is "-csv", for example, and if so call a separate function that loads a csv file nd enters a while loop as necessary.

Answer 4

I suggest you to write simple shell script to read file and pass parameters to your program in a while loop. Here for example described how to read csv file in bash. Check this also.

Answer 5

A much simpler approach would be to do something like this:

#include <stdio.h>

void doYourCalculation(int *iArray) { 
   /*do whatever you do*/
}

int main(int argc, char *argv[])
{
  int iArray[14];
  int i = 0;
  while(1){
    if(scanf("%d",&iArray[i]) != 1){
      break;
    }
    i++;
    if(i == 14) {
      i = 0;
      doYourCalculation(iArray);
    }
  }
  return 0;
}

And since you are using unix/linux, take advantage of the shell:

issue this command in the terminal:

$ cat your_data_file.dat | ScorecommandLine

Where your_data_file.dat looks like :

150 0 0 0 0 0 35 1 1 1 130 1 1 1
130 0 0 0 0 0 25 1 1 1 150 2 4 3
50 0 0 9 0 0 25 1 3 1 123 1 0 0
-

The - at the end marks end-of-input.

The philosophy of programming is to keep it as simple and accurate as possible.