Aligning printf() variables and decimals in C

Question

big problem with C today. So I want my variables to align in columns and be 2 decimal places at the same time.

I know to get to 2 decimal places I need to use %.2f and i

Answer 1

Try this:

    printf("ItemA\t\t%30.2f @ $3.34 \t\t$ %30.2f\n", huhu, totalhuhu);
    printf("ItemB\t\t%30.2f @ $44.50\t\t$ %30.2f\n", haha, totalhaha);

The \t are tabs to keep similar spacing. You can add as many as you want until you like it and %30.2f will give you a width of 30 before the decimal and a width of 2 after. This should give you your desired results for spacing.

Answer 2

Personally, I'd avoid tabs in the output. You can get the alignment to work if you're careful — primarily by using the same format string for each item. (Your choice of variable names makes that harder to fully automate; there are advantages to arrays of structures.)

If you want currency-sensitive formatting, look at the strfmon() function, and remember that a C program runs in the C locale until you set a different locale using setlocale().

Sample code:

#include <stdio.h>
#include <locale.h>
#include <monetary.h>

int main(void)
{
    double huhu = 123.45;
    double haha = 234.56;
    double huhu_price = 3.34;
    double haha_price = 44.50;
    double totalhuhu = huhu * huhu_price;
    double totalhaha = haha * haha_price;
    char *huhu_name = "Item A";
    char *haha_name = "Much Longer Name";

    setlocale(LC_ALL, "");

    const char fmt[] = "%-30s %10.2f @ $%6.2f $%20.2f\n";
    printf(fmt, huhu_name, huhu, huhu_price, totalhuhu);
    printf(fmt, haha_name, haha, haha_price, totalhaha);

    char buffer1[32];
    char buffer2[32];
    const char p_fmt[] = "%-30s %10.2f @ %s %s\n";
    const char price[] = "%(7.2n";
    const char cost[]  = "%(21.2n";
    strfmon(buffer1, sizeof(buffer1), price, huhu_price);
    strfmon(buffer2, sizeof(buffer2), cost, totalhuhu);
    printf(p_fmt, huhu_name, huhu, buffer1, buffer2);
    strfmon(buffer1, sizeof(buffer1), price, haha_price);
    strfmon(buffer2, sizeof(buffer2), cost, totalhaha);
    printf(p_fmt, haha_name, haha, buffer1, buffer2);

    return 0;
}

Sample output:

Item A                             123.45 @ $  3.34 $              412.32
Much Longer Name                   234.56 @ $ 44.50 $            10437.92
Item A                             123.45 @   $3.34               $412.32
Much Longer Name                   234.56 @  $44.50            $10,437.92