bool to_number ( const string& s, int& n ){ istringstream iss ( s ); return iss >> n; } bool to_number ( const string& s, float& n ){ istringstream iss ( s ); return iss >> n; } bool to_number ( const string& s, double& n ){ istringstream iss ( s ); return iss >> n; }
int n = 0; cout << to_number ( "234", n ) << endl; cout << n << endl; istringstream iss ( "123.45" ); //字符串輸入流 double num; if ( iss >> num ) cout << num << endl; ostringstream oss; oss << 543.21; string s = oss.str(); cout << s << endl;