CODEWITHSUNDEEP
c++inputoperatorscin
danielassayag
danielassayag

Reputation: 931

input a math operation in c++ using cin function

Here is a very basic program that simulates a log x(y) function.

I would like to know if it is possible to input a mathematical operation in the cin function.

For example to calculate log2(1/8) ? So input 2 for x and 1/8 for y

#include <iostream>
#include <cmath>
using namespace std;

int main() {
double x(0.0);
double y(0.0);

cout << "log" << endl;
cin >> x;
cout << "result" << endl;
cin >> y;

double loga = log(y) / log(x);

cout << "log" << x << "(" << y << ") =" << loga << endl;

cout << loga << "^" << x << "="<< pow(x, loga)<< endl;

return 0;
}

thank you for your help

Upvotes: 0

Views: 3657

Answers (3)

Baum mit Augen
Baum mit Augen

Reputation: 50061

No, cin cannot do that. You would have to read the expression as a string, then parse it and evaluate it to a number.

Resources on how to do this for simple cases are easily found online and there are powerful libraries that can do the work for you.

Upvotes: 1

Soner from The Ottoman Empire
Soner from The Ottoman Empire

Reputation: 20891

cin doesn't support your intent. However, you can follow an approach that hold your fractional expression in a string than convert it as double value. So go on.

Upvotes: 1

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

I would like to know if it is possible to input a mathematical operation in the cin function.

It's only possible by means you write your own parser, that translates the input achieved from std::cin or any other std::istream source that isn't covered from any standard translations like int, long, float, std::string etc.

Do you should provide logic to parse the input you get and translate that to values and function call logic.

Upvotes: 1

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