formatting.adoc

To print tabulated fields in plain text I first divide the desired ouput by the number of columns each field should take. For example:

    dni         name                 birdthdate
    12345678 Ana Allen               12/10/1998
<- 12 col -><------ 24 col --------><- 12 col ->

I like to use multiples of 4, but multiples of 8 or 10 are good options too. The nice thing about 4 is that it aligns with my text editor’s default tabstop setting. It helps when writting report headers.

Note	Left-aligned fields after a right-aligned field need a space in between. I like to just add the space to all left-aligned fields.

Warning

Macros are useful, but don’t abuse them. They are hard to debug.

Example implementation:

//[aux.h]

/* Stream manipulator macros
 * =========================
 */

#include <iostream>
#include <iomanip>

// The parenthesis in C/C++ macros are best practice
// https://stackoverflow.com/q/7186504/7498073

// Width-Left (use with strings)
#define WL(w)           " " << setw((w) - 1) << left

// Width-Right (use with numbers)
#define WR(w)           setw(w) << right << setprecision(2) << fixed

// Width-Right-0-padding
#define WR0(w, w0, x)   setw((w) - (w0)) << "" \
                        << setw(w0) << right << setfill('0') \
                        << setprecision(2) << fixed << (x) \
                        << setfill(' ')

// Width-Left-Date (dd/mm/yyyy format)
#define WLD(w, x)       setw((w) - 10) << "" << WR0(2, 2, (x) % 100) \
                        << '/' << WR0(2, 2, (x) / 100 % 100) \
                        << '/' << WR0(4, 4, (x) / 10000)

// (for character arrays)
#define MAXLEN          100
// (for static arrays of items)
#define MAXITEMS        1000

Example usage:

//[example.cpp]

/* Example usage
 * ============= */

#include "aux.h"      // It's easier to import a single .h to many .cpp files

using namespace std;

typedef struct {
    int id;
    const char name[MAXLEN];
    double luckynumber;
    int dob;    // date of birth
} student_t;

int main(int argc, char *argv[])
{
    student_t students[] = {
        {1, "Ana Ambooken", 69.420, 19990606},
        {2, "Bob Banana", 666.66, 19760411},
        {3, "Carlos Clear", 123.456, 20000101}
    };
    int n = 3;

    for (int i = 0; i < n; i++) {
        cout << WR0(8, 4, students[i].id)
             << WL(40) << students[i].name
             << WR(8) << students[i].luckynumber;
        cout << WLD(12, students[i].dob);
        cout << '\n';
    }
    return 0;
}

Output:

    0001 Ana Ambooken                              69.42  06/06/1999
    0002 Bob Banana                               666.66  11/04/1976
    0003 Carlos Clear                             123.46  01/01/2000