C ++ bash管道内存

Question

I'm using what I heard is "bash pipe command" to run multiple input files through multiple modification programs. Example command:

cat input1.cpp input2.cpp input3.cpp | ./calc | ./rmv_comments | ./calc

With this command I first run 3 different files through a program that calculate characters combined in the files, 230 + 450 + 100 = 780 for example. Once that is done, comments from all input files are removed. After all comments are removed I need to run the calculation program again to get the amount of reduction in characters.

My problem is that once I run the rmv_comments program between the calculations I no longer know how many characters I had originally. How or where can I store the amount of character originally? Also, how can I cout or printf the amount of reduction without messing with the output that is redirected as an input to rmv_comments?

calc.cpp :

int main()
{
    char c;
    int count;

    while(cin.get(c))
    {
        count++;

        cout << c;
    }

    // How do I store "OLDCOUNT" when this program (calc.cpp) run the first time?
    int reduction = (1 - count/OLDCOUNT) * 100;

    // How can I printf or cout the result ONLY to command line
    // NOT to output (input of rmv_comments)
    printf("Reduction: %d", reduction);

    return 0;
}

rmv_comments.cpp :

int main()
{
    string line;
    while(getline(cin, line))
    {
        char c;
        string tmp;
        for(int i=0; i<line.length(); i++)
        {
            if(line[i] == '/' && line[i+1] == '/')
                break;

            tmp += line[i];
        }
        cout << tmp << endl;
    }

    return 0;
}

Answer 1

How about using a file to store the value?

If the doesn't exist, then you know it's a first run, you do your calculations and create the file and store whatever data you need to store.

If the file exist, it's the second run, and you load the data from the file and then remove the file.