std::quoted
From cppreference.com
Defined in header <iomanip>
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template
<
class CharT >
/*unspecified*/ quoted( const CharT* s, |
(1) | (since C++14) |
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template
<
class CharT, class Traits, class Allocator >
/*unspecified*/ quoted(
const
std::basic_string
<CharT, Traits, Allocator>
& s, |
(2) | (since C++14) |
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template
<
class CharT, class Traits>
/*unspecified*/ quoted(
std::basic_string_view
<CharT, Traits> s, |
(3) | (since C++17) |
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template
<
class CharT, class Traits, class Allocator >
/*unspecified*/ quoted(
std::basic_string
<CharT, Traits, Allocator>
& s, |
(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 overloads (2,3), traits_type equal to Traits, behaves as a FormattedOutputFunction, which inserts into out a sequence of characters seq
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() , adds out.width()-seq.size() copies of the fill character out.fill() either at the end of the sequence (if ios_base::left is set in out.flags()
- Finally, outputs each character from the resulting sequence as if by calling out.rdbuf()->sputn(seq, n) , where n= std::max (out.width ( ), seq.size ( ) ) and out.width(0) to cancel the effects of std::setw
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>>
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
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<<
Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_quoted_string_io |
201304L |
(C++14) | std::quoted
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Example
Run this code
#include <iomanip> #include <iostream> #include <sstream> void default_delimiter() { const std::string in = "std::quoted() quotes this string and embedded \"quotes\" too"; std::stringstream ss; ss << std::quoted(in); std::string out; ss >> std::quoted(out); std::cout << "Default delimiter case:\n" "read in [" << in << "]\n" "stored as [" << ss.str() << "]\n" "written out [" << out << "]\n\n"; } void custom_delimiter() { const char delim{'$'}; const char escape{'%'}; const std::string in = "std::quoted() quotes this string and embedded $quotes$ $too"; std::stringstream ss; ss << std::quoted(in, delim, escape); std::string out; ss >> std::quoted(out, delim, escape); std::cout << "Custom delimiter case:\n" "read in [" << in << "]\n" "stored as [" << ss.str() << "]\n" "written out [" << out << "]\n\n"; } int main() { default_delimiter(); custom_delimiter(); }
Output:
Default delimiter case: read in [std::quoted() quotes this string and embedded "quotes" too] stored as ["std::quoted() quotes this string and embedded \"quotes\" too"] written out [std::quoted() quotes this string and embedded "quotes" too] Custom delimiter case: read in [std::quoted() quotes this string and embedded $quotes$ $too] stored as [$std::quoted() quotes this string and embedded %$quotes%$ %$too$] written out [std::quoted() quotes this string and embedded $quotes$ $too]
See also
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(C++20)
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stores formatted representation of the arguments in a new string (function template) |