C++ Error: no match for call to ‘(std::string {aka std::basic_string

When I want to use string::s(unsigned, char) to assigned s, the g++ output this error message.

There is my class:

#include <string>
using std::string;

class Screen()
{
private:
    unsigned height = 0, width = 0;
    string contents;
public:
    Screen(unsigned ht, unsigned wd): height(ht), width(wd) {contents(ht * wd, ‘ ’）；}
}

Why it is wrong?

I know that it should be Screen(unsigned ht, unsigned wd): height(ht), width(wd), contents(ht * wd, ‘ ’）{ }, but why I can't use the functionstring(unsigned, char) to assigned a value for a string constructed?