How to Pass a std::string variable into a function

I have a C++ method that takes one variable the method signature is like this:

DLL returnObject** getObject( const std::string folder = "" );

I tried passing in:

const std::string myString = "something";

but I get the following error:

No matching function call to ... getObject( std::string&);

I have a couple questions here.

1. How do I pass in a n开发者_运维问答ormal std::string without the &
2. This looks like the value is optional folder = "" is it? And if so how do you pass an optional parameter?

---

This little example works as expected:

#include <stdio.h>
#include <string>

class foo {
public:
    void getObject( const std::string folder = "" );
};

int main ()
{
    const std::string myString = "something";

    foo* pFoo = new foo;

    pFoo->getObject( myString);
    pFoo->getObject();    // call using default parameter

    return 0;
}


void foo::getObject( const std::string folder)
{
    printf( "folder is: \"%s\"\n", folder.c_str());
}

You might want to post a similarly small example that shows your problem.

---

This compiled fine for me, compare it to what you're doing:

#include <string>

void myFunc(const std::string _str)
{
}

int main()
{
    const std::string str = "hello world";
    myFunc(str);
    return 0;
}