Program

[pacman169]

Hello!

I bought a C++ book and have started trying the example. Here is a code:

#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>
using namespace std;
inline void keep_window_open() {char ch; cin>>ch;}

int main()
{
     cout<< "Please enter a floating-point value:";
     double n;
     cin>>n;
     cout<< "n =="<<n
         << "\nn+1 =="<<n+1
         << "\nthree times n=="<<3*n
         << "\ntwice n=="<<n+n
         << "\nn squared=="<<n*n
         << "\nhalf of n=="<<n/2
         << "\nsquare root of n=="<<sqrt(n)
         << "\n";  // another name for newline ("end of line") in output

}

Now There is exercise:

Get this little program to run. Then, modify it to read an int rather than a double. Note that sqrt() is not defined for an int so assign n to a double and take sqrt() of that.

How should I do this? I get error message when trying do change the code.

[mutexe]

You haven't showed us your modified code or the error message(s), so i'm not sure how anyone can help. Other than writing it for you.

edit: here you go.

#include<iostream>

int main()
{
	std::cout<< "Please enter a integer value:";
	int n;
	std::cin>>n;

	double nAsDouble = static_cast<double>(n);

	std::cout<< "n =="<<n
		<< "\nn+1 =="<<n+1
		<< "\nthree times n=="<<3*n
		<< "\ntwice n=="<<n+n
		<< "\nn squared=="<<n*n
		<< "\nhalf of n=="<<n/2
		<< "\nsquare root of n=="<<sqrt(nAsDouble)
		<< "\n";  // another name for newline ("end of line") in output

	return 0;
}

[pacman169]

Ok thanks for your reply. In the part where you assign n to a double you write

double nAsDouble = static_cast<double>(n);

however I have never learned that one. Would it be possible to assign n to double just by writing

n=double ?

[xenovia12]

If im not mistaken you are using bjatne strustrup book

[pacman169]

Yes that`s true but how about my question?

Thank you for your interest.

[j3Rz8vqX]

n=double is invalid: n being a variable and double being a data type.

Another solution would be cast n to double then assign it: double nAsDouble = (double) n;

or simply assign n to a double:
A double has more precision, it would do little harm, if any: double nAsDouble = n;.

[mutexe]

Another solution would be cast n to double then assign it: double nAsDouble = (double) n;

That's what i did in my code in my earlier post. i just used the safer c++ conventional cast.

OP, if you're using C++ and not C (which you are) i would stay away C-style casts that Dput is recommending.