Does put_time Have a Conversion Specifier Which Outputs Single Digit Days of the Month Without a Preceding Character

Question

put_time provides 2 conversion specifiers for outputting day of the month:

1. %d: "Day of the month, zero-padded (01-31)"
2. %e: "Day of the month, space-padded ( 1-31)"

Note that neither of these conversion specifiers will allow me to output a non-padded day of the month. So for example, given tm tmb, if I want to output the day of the month as:

Feb 8 '18

I could do: cout << put_time(&tmb, "%b%e '%y")

But that on the 10^th that will output:

Feb10 '18

Thus I must do the janky: cout << put_time(&tmb, "%b ") << tmb.tm_mday << put_time(&tmb, " '%y")

Is there a conversion specifier that I can use to get this all in a single put_time call?

Answer 1

To answer this I've pulled what I believe is a comprehensive list of the conversion specifiers from here: http://en.cppreference.com/w/cpp/io/manip/put_time and bundled them into a simple program:

tm tmb = { 5, 6, 7, 8, 9, 10 };

mktime(&tmb);

for(const auto i : { "%%", "%n", "%t", "%Y", "%EY", "%y", "%Oy", "%Ey", "%C", "%EC", "%G", "%g", "%b", "%h", "%B", "%m", "%Om", "%U", "%OU", "%W", "%OW", "%V", "%OV", "%j", "%d", "%Od", "%e", "%Oe", "%a", "%A", "%w", "%Ow", "%u", "%Ou", "%H", "%OH", "%I", "%OI", "%M", "%OM", "%S", "%OS", "%c", "%Ec", "%x", "%Ex", "%X", "%EX", "%D", "%F", "%r", "%R", "%T", "%p", "%z", "%Z" } ) {
    cout << i << "\t|\t\"" << put_time(&tmb, i) << "\"\n";
}

The output of this looks like this:

%%  |   "%"
%n  |   "
"
%t  |   "   "
%Y  |   "1910"
%EY |   "1910"
%y  |   "10"
%Oy |   "10"
%Ey |   "10"
%C  |   "19"
%EC |   "19"
%G  |   "1910"
%g  |   "10"
%b  |   "Oct"
%h  |   "Oct"
%B  |   "October"
%m  |   "10"
%Om |   "10"
%U  |   "40"
%OU |   "40"
%W  |   "40"
%OW |   "40"
%V  |   "40"
%OV |   "40"
%j  |   "281"
%d  |   "08"
%Od |   "08"
%e  |   " 8"
%Oe |   " 8"
%a  |   "Sat"
%A  |   "Saturday"
%w  |   "6"
%Ow |   "6"
%u  |   "6"
%Ou |   "6"
%H  |   "07"
%OH |   "07"
%I  |   "07"
%OI |   "07"
%M  |   "06"
%OM |   "06"
%S  |   "05"
%OS |   "05"
%c  |   "Sat Oct  8 07:06:05 1910"
%Ec |   "Sat Oct  8 07:06:05 1910"
%x  |   "10/08/10"
%Ex |   "10/08/10"
%X  |   "07:06:05"
%EX |   "07:06:05"
%D  |   "10/08/10"
%F  |   "1910-10-08"
%r  |   "07:06:05 AM"
%R  |   "07:06"
%T  |   "07:06:05"
%p  |   "AM"
%z  |   "+0000"
%Z  |   "UTC"

The field in question is the tmb.tm_mday which is populated with an 8. Thus what you'd need here is a value in the table of "8". A quick search will demonstrate there isn't one. Thus, the answer to your question is: There is no conversion specifier which outputs single digit days of the month without a preceding character. You will have to use a workaround similar to what you've proffered in the question.