error: default argument given for parameter 1

I'm getting this error message with the code below:

c开发者_Go百科lass Money {
public:
    Money(float amount, int moneyType);
    string asString(bool shortVersion=true);
private:
    float amount;
    int moneyType;
};

First I thought that default parameters are not allowed as a first parameter in C++ but it is allowed.

You are probably redefining the default parameter in the implementation of the function. It should only be defined in the function declaration.

//bad (this won't compile)
string Money::asString(bool shortVersion=true){
}

//good (The default parameter is commented out, but you can remove it totally)
string Money::asString(bool shortVersion /*=true*/){
}

//also fine, but maybe less clear as the commented out default parameter is removed
string Money::asString(bool shortVersion){
}

I made a similar error recently. this is how I resolved it.

when having a function prototype and definition. the default parameter is not specified in the definition.

eg:

int addto(int x, int y = 4);

int main(int argc, char** argv) {
    int res = addto(5);
}

int addto(int x, int y) {
    return x + y;
}