The code below is working on c++98 but not on c++11 or c++14...please help

Question

#include <iostream>
using namespace std;

class system
{
double amount;
public:
system(double a)
{
amount = a;
cout << amount;
}

};

int main()
{
double n;
cout << "Please enter the amount number : ";
cin >> n;
system obj(n);
}

the error is :-

source_file.cpp: In function 'int main()':
source_file.cpp:21:14: error: expected ';' before 'obj'
system obj(n);
^~~
source_file.cpp:21:20: warning: statement is a reference, not call, to function 'system' [-Waddress]
system obj(n);
^
source_file.cpp:21:20: warning: statement has no effect [-Wunused-value]

Answer 1

You need to use capital letters for the first letter of your class, change 'system' to 'System'

Answer 2

Actually, system is a build-in function ( which you shouldn't be using anyway ) defined in cstdlib, which is included through iostream.
So you have a name collision here.

But just like jtrh said, you should name the class starting with a capital.

Answer 3

thanks alot jtrh 😃😃
but why is it so?
why can't I write in lowercase?
Is it a convention in new c++?

Answer 4

It was optional to follow naming conventions in old c++ but now I guess it is compulsory. It's good practice though