Mc Lauren Series wrote:
#include<iostream>
#include<sstream>
using namespace std;
int main()
{
string a("test");
string b;
stringstream(a)>> b;
}
When I try to execute this code, I get errors:
foo.c: In function 'int main()':
foo.c:10: error: no match for 'operator>>' in
'std::basic_stringstream<char, std::char_traits<char>,
std::allocator<char> >(((const std::basic_string<char,
std::char_traits<char>, std::allocator<char> >&)((const
std::basic_string<char, std::char_traits<char>, std::allocator<char>
*)(& a))), std::operator|(_S_out, _S_in))>> b'
Why does this error occur? Isn't stringstream(a) supposed to behave
just like a stream? With cout I can extract string into a string
variable. Then why not here?
The operator>> is a non-member. It takes the first argument by a
non-const reference, which cannot be initialized with a temporary.
Define a named variable and you will be able to do what you want:
stringstream sa(a);
sa>> b;
There is a trick to overcome this particular limitation, but it's not
the best approach. You can do something like that
stringstream(a)>> boolalpha>> b;
which invokes a non-const member function (which is OK for temporaries)
and the function (that "outputs" a manipulator) returns a non-const
reference, which then can be passed to the non-member operator<<.