61

For C programming. How do i get numbers to be displayed as 00, 01, 02, 03, instead of 0, 1, 2, 3. I just need 0 before the number until 10.

i know when your doing decimals you can do "%.2f" etc. but what about in reverse for integers?

here is what I am using...**

printf("Please enter the hours: ");
    scanf ("%d",&hour);
printf("Please enter the minutes: ");
    scanf ("%d",&minute);
printf("Please enter the seconds: ");
    scanf ("%d",&second);
printf("%d : %d : %d\n", hour, minute, second);

}

I need the numbers to display as 00 : 00 : 00

??

Adeel Anwar
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3 Answers3

89

You need to use %02d if you want leading zeroes padded to two spaces:

printf ("%02d : %02d : %02d\n", hour, minute, second);

See for example the following complete program:

#include <stdio.h>
int main (void) {
    int hh = 3, mm = 1, ss = 4, dd = 159;
    printf ("Time is %02d:%02d:%02d.%06d\n", hh, mm, ss, dd);
    return 0;
}

which outputs:

Time is 03:01:04.000159

Keep in mind that the %02d means two characters minimum width so it would output 123 as 123. That shouldn't be a problem if your values are valid hours, minutes and seconds, but it's worth keeping in mind because many inexperienced coders seem to make the mistake that 2 is somehow the minimum and maximum length.

paxdiablo
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    what is the solution for tuning the maximum length? – rahman Jun 20 '17 at 13:24
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    @rahman, there's no good solution for specifying maximum length. If you have the value `123` and you shoehorn it into two digits, you'll get one of `12` or `23`, depending on how you decide to do it. Neither of those is acceptable in my opinion. Far better to output `**` as an indication that something's gone horribly wrong. – paxdiablo Jul 01 '20 at 13:57
  • This also works for hexa printf("%02X", ... ); – Stoica Mircea Aug 02 '22 at 14:25
44

Use the format: %02d instead. The 0 means to pad the field using zeros and the 2 means that the field is two characters wide, so for any numbers that take less than 2 characters to display, it will be padded with a 0.

dreamlax
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5

"%.2d" is what should be used. The rule is basically;

"%<minimum-characters-overall>.<minimum-digits>d".

For example:

"%6.3d" will print 6 characters overall and a minimum of 3 digits.

Letladi Sebesho
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