13template <
class T>
constexpr T
abs(T x)
noexcept {
return x < 0 ? - x : x;}
25 return ch ==
'0' or ch ==
'1' or ch ==
'2' or ch ==
'3' or
26 ch ==
'4' or ch ==
'5' or ch ==
'6' or ch ==
'7' or
27 ch ==
'8' or ch ==
'9';
40 return ch ==
' ' or ch ==
'\n' or ch ==
'\r' or ch ==
'\t' or ch ==
'\f' or
53constexpr bool isnan(
double d)
noexcept {
return d not_eq
d;}
54constexpr bool isnan(
long double d)
noexcept {
return d not_eq
d;}
55constexpr bool isnan(
float d)
noexcept {
return d not_eq
d;}
constexpr T abs(T x) noexcept
constexpr int isdigit(int ch) noexcept
constexpr bool isnan(double d) noexcept
constexpr int isspace(int ch) noexcept
Returns 1 if x is a standard space-character.