CODEWITHSUNDEEP
c++
Alex U
Alex U

Reputation: 1

How to recognize the type of data in C++?

I learn C++ by a book, and always when I have a task to do, I'll add some of my features. Now I wanted to add "check for dummy people", and if they write fractional number, not integer, the console will be closed. I wanted to do like that:

cin >> timing;
if (timing == double) { 
    ...

But the Visual Studio compiler says "type name is not allowed".

Please, tell me how to do this check

Upvotes: 0

Views: 81

Answers (1)

bitmask
bitmask

Reputation: 34628

The type of your timing variable is static, as are all types in C++. I'm going to assume it's an std::string. It will never be a double or an int. What you can do with it, is translate the information stored in it into another object of a different type.

For example, with std::stod you can try and convert the string into a double. This will return a double for all inputs, e.g. "3.1", "0", "horse", or "". For the last two, however conversion will fail, and std::stod will throw. However, the return value is always a double.

Now, you can check if the double holds an integral value. For instance you can convert the value to long and back and check if you get the same value. There are more sophisticated ways to check this, but it would be a good start.

Upvotes: 1

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