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How to pass std::string as default parameter

gilgil

http://www.gilgil.net/?document_srl=10729

2011.10.18 20:45:59 (*.4.203.182)

107170

When passing std::string is passed, object is copied through a stack.

void loadFromFile(std::string fileName);

So, parameter is passed in reference type to prevent object copy load in the stack.

void loadFromFile(std::string& fileName);

But, if the argument is in default argument format, compile error occurs.

void loadFromFile(std::string& fileName = ""); // compile error

If you would like to use string as default argument, the following code is preferable.

const static std::string NULL_STR = "";
void foo_str(const std::string& fileName = NULL_STR)

You would..

List

2012.07.23 19:06:00 (*.170.135.179)

Lyn

void foo(const std::string& name = "") <<-- OK

void foo(string& name = string()) <<-- OK2

void foo(string& name = string("DefaultString")) <<-- OK3

but so slow...
this code makes temp object...

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