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stringstream constructor

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this code
std::stringstream info();
info << point.x << point.y << point.z << u << v;
OutputDebugString(info.str().c_str());
causes this error
error C2296: '<<' : illegal, left operand has type 'std::stringstream (__cdecl *)(void)'
error C2297: '<<' : illegal, right operand has type 'const float'
error C2228: left of '.str' must have class/struct/union
error C2228: left of '.c_str' must have class/struct/union
though this code (omit parentheses)
std::stringstream info  ;
info << point.x << point.y << point.z << u << v;
OutputDebugString(info.str().c_str());
yields no error, but im unconvinced that it is correct. shouldn't they have identical functionality anyway? whats up? x,y,z are floats

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std::stringstream info(); doesn't actually construct a stringstream called info. It declares a function called info that returns a stringstream and takes no parameters. It's equivalent to std::stringstream info(void);

Basically you'll have to live without the parenthesis.

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Quote:
std::stringstream info();
The compiler parses this as a function prototype and gets confused (this is why we omit the parentheses in this context, as in your second example).

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std::stringstream info();


This is declaration of a function and it doesn't do what you want it to.


class X
{
X( int y = 17 );
}


X x(y);


or

X x; // same as x(17);



are declarations of a variable.

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