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std::basic_istringstream::str(3) | C++ Standard Libary | std::basic_istringstream::str(3) |
NAME¶
std::basic_istringstream::str - std::basic_istringstream::str
Synopsis¶
std::basic_string<CharT,Traits,Allocator> str() const;
(until C++20)
std::basic_string<CharT,Traits,Allocator> str() const&; (since
C++20)
template<class SAlloc>
std::basic_string<CharT,Traits,SAlloc> str( const SAlloc& a )
(2) (since C++20)
const;
std::basic_string<CharT,Traits,Allocator> str() &&; (1)
(3) (since C++20)
void str( const std::basic_string<CharT,Traits,Allocator>& s
(4)
);
template<class SAlloc> (5) (since C++20)
void str( const std::basic_string<CharT,Traits, SAlloc>& s );
void str( std::basic_string<CharT,Traits,Allocator>&& s );
(6) (since C++20)
Manages the contents of the underlying string object.
1) Returns a copy of the underlying string. Equivalent to return
rdbuf()->str();.
2) Returns a copy of the underlying string, using a as allocator. Equivalent
to
return rdbuf()->str(a);.
3) Returns a string move-constructed from the underlying string. Equivalent
to
return std::move(*rdbuf()).str();.
4-5) Replaces the contents of the underlying string. Equivalent to
rdbuf()->str(s);.
6) Replaces the contents of the underlying string. Equivalent to
rdbuf()->str(std::move(s));.
Parameters¶
s - new contents of the underlying string
a - allocator used to construct the returned string
Return value¶
1-2) a copy of the underlying string object.
3) a string move-constructed from the underlying string object.
4-6) (none)
Notes¶
The copy of the underlying string returned by str is a temporary
object that will be
destructed at the end of the expression, so directly calling c_str() on the
result
of str() (for example in auto *ptr = out.str().c_str();) results in a
dangling
pointer.
Example¶
// Run this code
#include <sstream>
#include <iostream>
int main()
{
int n;
std::istringstream in; // could also use in("1 2")
in.str("1 2");
in >> n;
std::cout << "after reading the first int from \"1 2\",
the int is "
<< n << ", str() = \"" << in.str() <<
"\"\n";
std::ostringstream out("1 2");
out << 3;
std::cout << "after writing the int '3' to output stream \"1
2\""
<< ", str() = \"" << out.str() <<
"\"\n";
std::ostringstream ate("1 2", std::ios_base::ate);
ate << 3;
std::cout << "after writing the int '3' to append stream \"1
2\""
<< ", str() = \"" << ate.str() <<
"\"\n";
}
Output:¶
after reading the first int from "1 2", the int is 1,
str() = "1 2"
after writing the int '3' to output stream "1 2", str() = "3
2"
after writing the int '3' to append stream "1 2", str() = "1
23"
See also¶
rdbuf returns the underlying raw string device object
(public member function)
str replaces or obtains a copy of the associated character string
(public member function of
std::basic_stringbuf<CharT,Traits,Allocator>)
2022.07.31 | http://cppreference.com |