cpp/io/manip/showpoint

Enables or disables the unconditional inclusion of the decimal point character in floating-point output. Has no effect on input.

@1@ enables the flag in the stream  as if by calling @2@ disables the flag in the stream  as if by calling

This is an I/O manipulator, it may be called with an expression such as for any  of type std or with an expression such as  for any  of type std.

The character to use as decimal point character is determined by the numpunct facet of the locale imbued in the stream at the time of output, as described in std

Return value
(reference to the stream after manipulation)