how to use the outcome of prgram in another program

Question

I have a Ruby program that transforms a tabel to a grammar.

The output looks like "GRAMMAR = {" bla bla bla }

in a second program a use this grammar as input for performing another task.

What I do now is copy/paste the outcome of the first program in the second program. I want to combine the programs into one program. In other words: how can I make the outcome of the fist as a public variable in the second?

Answer 1

There are 2 fundamental ways to deal with this.

Pass data between functions

You could turn your programs into individual functions, and you could pass data between these functions. Whatever Function 1 returns (make it return outpu as data, instead of printing it on the screen) should be consumed as a parameter by Function 2.

I do not know Ruby, but you can look at this tutorial to learn about functions.

In C, the code would look something like this.

#include <stdio.h>

char * Function1()
{
    char * data = NULL/* produce your data, instead of NULL */;
    return data;
}

void Function2(const char * data)
{
    // Do someting with data
}

int main()
{
    char * dataFromFunction1 = Function1();
    Function2(dataFromFunction1);
    
    return 0;
}

Pass data between programs

You can keep your individual programs and connect them together. This assumes a Program1 writes the standard output while Program2 reads the standard input.

Then, in a command shell you could invoke Program1 and pipe its output to Program2. It would look something like this:

Program1 | Program2

This needs you to run your command in a shell. If you use the OnlineGDB, then you can save the output as a file instead in Program1 and read from a file in Program2