30 Regular expressions library [re]

30.6 Class template regex_­traits [re.traits]

Table 143: Character class names and corresponding ctype masks [tab:re.traits.classnames]
Narrow character name
Wide character name
Corresponding ctype_­base​::​mask value
"alnum"
L"alnum"
ctype_­base​::​alnum
"alpha"
L"alpha"
ctype_­base​::​alpha
"blank"
L"blank"
ctype_­base​::​blank
"cntrl"
L"cntrl"
ctype_­base​::​cntrl
"digit"
L"digit"
ctype_­base​::​digit
"d"
L"d"
ctype_­base​::​digit
"graph"
L"graph"
ctype_­base​::​graph
"lower"
L"lower"
ctype_­base​::​lower
"print"
L"print"
ctype_­base​::​print
"punct"
L"punct"
ctype_­base​::​punct
"space"
L"space"
ctype_­base​::​space
"s"
L"s"
ctype_­base​::​space
"upper"
L"upper"
ctype_­base​::​upper
"w"
L"w"
ctype_­base​::​alnum
"xdigit"
L"xdigit"
ctype_­base​::​xdigit