std::quoted
std::quoted
Defined in header <iomanip> | ||
---|---|---|
template< class CharT > /*unspecified*/ quoted(const CharT* s, CharT delim=CharT('"'), CharT escape=CharT('\\')); | (1) | (since C++14) |
template< class CharT, class Traits, class Allocator > /*unspecified*/ quoted(const std::basic_string<CharT, Traits, Allocator>& s, CharT delim=CharT('"'), CharT escape=CharT('\\')); | (2) | (since C++14) |
template< class CharT, class Traits> /*unspecified*/ quoted(std::basic_string_view<CharT, Traits> s, CharT delim=CharT('"'), CharT escape=CharT('\\')); | (3) | (since C++17) |
template< class CharT, class Traits, class Allocator > /*unspecified*/ quoted(std::basic_string<CharT, Traits, Allocator>& s, CharT delim=CharT('"'), CharT escape=CharT('\\')); | (4) | (since C++14) |
Allows insertion and extraction of quoted strings, such as the ones found in CSV or XML.
1-3) When used in an expression
out << quoted(s, delim, escape)
, where out
is an output stream with char_type
equal to CharT
and, for overload 2, traits_type
equal to Traits
, behaves as a FormattedOutputFunction
, which inserts into out
a sequence of characters seq
constructed as follows:
a) First, the character
delim
is added to the sequence
b) Then every character from
s
, except if the next character to output equals delim
or equals escape
(as determined by the stream's traits_type::eq
), then first appends an extra copy of escape
c) In the end,
delim
is appended to seq
once more - Then, if
seq.size() < out.width()
, addsout.width()-seq.size()
copies of the fill characterout.fill()
either at the end of the sequence (ifios_base::left
is set inout.flags()
) or at the beginning of the sequence (in all other cases). - Finally, outputs each character from the resulting sequence as if by calling
out.rdbuf()->sputn(seq, n)
, wheren=std::max(out.width(), seq.size())
andout.width(0)
to cancel the effects ofstd::setw
, if any.
4) When used in an expression
in >> quoted(s, delim, escape)
, where in
is an input stream with char_type
equal to CharT
and traits_type
equal to Traits
, extracts characters from in
, using std::basic_istream::operator>>
, according to the following rules:
a) If the first character extracted does not equal
delim
(as determined by the stream's traits_type::eq
), then simply performs in >> s
.
b) Otherwise (if the first character is the delimiter):
1) Turns off the
skipws
flag on the input stream
2) Empties the destination string by calling
s.clear()
3) Extracts characters from
in
and appends them to s
, except that whenever an escape
character is extracted, it is ignored and the next character is appended to s
. Extraction stops when !in==true
or when an unescaped delim
character is found.
4) Discards the final (unescaped)
delim
character.
5) Restores the
skipws
flag on the input stream to its original value.Parameters
s | - | the string to insert or extract |
delim | - | the character to use as the delimiter, defaults to " |
escape | - | the character to use as the escape character, defaults to \ |
Return value
Returns an object of unspecified type such that the described behavior takes place.
Exceptions
Throws std::ios_base::failure
if operator>>
or operator<<
throws.
Example
#include <iostream> #include <iomanip> #include <sstream> int main() { std::stringstream ss; std::string in = "String with spaces, and embedded \"quotes\" too"; std::string out; ss << std::quoted(in); std::cout << "read in [" << in << "]\n" << "stored as [" << ss.str() << "]\n"; ss >> std::quoted(out); std::cout << "written out [" << out << "]\n"; }
Output:
read in [String with spaces, and embedded "quotes" too] stored as ["String with spaces, and embedded \"quotes\" too"] written out [String with spaces, and embedded "quotes" too]
See also
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