It says 'use' on the line int n = plus(3,4); .I dunno why though. Is it my compiler's (Dev C++) problem once again?Code:#include <iostream> #include <string> using namespace std; int plus(const int& val1,const int& val2); double plus(const double& val1,const double& val2); string plus(const string& val1,const string& val2); int main() { int n = plus(3,4); // error here double d = plus(3.2,4.2); string s = plus("he","llo"); string s1 = "aaa"; string s2 = "bbb"; string s3 = plus(s1,s2); cout << "n = " << n; << "d = " << d; << "s = " << s; << "s1 = " << s1; << "s2 = " << s2; << "s3 = " << s3 << endl << endl; system("PAUSE"); return 0; } int plus(const int& val1,const int& val2) { return val1 + val2 } double plus(const double& val1,const double& val2) { return val1 + val2 } string plus(const string& val1,const string& val2) { return val1 + val2 }