Default string arguments

Question

myPreciousFunction(std::string s1 = "", std::string s2 = "")
{
}

int main()
{
    myPreciousFunction();
}

can i make the arguments look any more prettier? i want there to be empty string if no arguments were supplied.

Answer 1

You can omit the namespace qualifier to make it look cleaner.

using namespace std;

void myPreciousFunction(string s1 = "", string s2 = "")
{
}

Answer 2

An alternative is to use overloaded functions, e.g.

myPreciousFunction(std::string s1, std::string s2)
{
   // primary implementation
}

myPreciousFunction(std:string s1)
{
    myPreciousFunction(s1, "");
}
myPreciousFunction()
{
    myPreciousFunction("", "");
}

Though I'm not sure this is any prettier, and definitely less attractive code-wise. (Default arguments are there to avoid this.)

Answer 3

you may consider this:

myPreciousFunction(std::string s1 = std::string(), std::string s2 = std::string())
{
}

But it doesn't really look prettier.

Also, if you're passing strings, you might want to pass them as const&:

myPreciousFunction(const std::string& s1, const std::string& s2)
{
}

This is a standard way to avoid coping the data around.

Answer 4

#define PRETTY std::string s1="", std::string s2=""
myPreciousFunction(PRETTY){}

:)

Answer 5

from the comments....

use

using namespace std;

above all... you don't need to write std::string anywhere you can write just string....

Answer 6

There is actually another solution.

const std::string empty = std::string();

myPreciousFunction( const std::string &s1 = empty, const std::string &s2 = empty)

This has the advantage of avoiding construction of temporary objects.