How do I reject inputs that are not numbers?

Asked Oct 16 '19 at 20:03

Active Oct 16 '19 at 20:11

Viewed 103 times

My program is a currency converter. Currently, my code works to convert currency but if the user were to type in characters rather than a number, it enters an infinite loop. This is the part of my code that I need to add something to verify the data.

void menu_item_4() {
  std::cout << "\n>> EUR to GBP\n";
  std::cout << "\nEnter a value to convert from EUR to GBP\n";
  float EUR_GBP;
  std::cin >> EUR_GBP;
  float eur_gbp = EUR_GBP * 0.86;
  std::cout << EUR_GBP << " EUR is equal to " << eur_gbp << " GBP.";
  go_back_to_main();
}

Let me know what I can do.

edited Oct 16 '19 at 20:08

Jerry Coffin

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asked Oct 16 '19 at 20:03

Ethan Quesne

First define "numbers". Is `-0.3` a number? How about `3.9e4`? – tadman Oct 16 '19 at 20:04
@tadman "number" doesn't need to be defined in a question. It's common knowledge – HAL9000 Oct 16 '19 at 20:05
This might have something useful. https://stackoverflow.com/questions/23958008/having-to-input-value-twice-to-work-c/ – Dortimer Oct 16 '19 at 20:11
1

@HAL9000 Some people are surprised by what C++ thinks is a number if left to its own devices. – tadman Oct 16 '19 at 20:37
Rather than a `go_back_to_main()` function, consider using the `return` statement. – Thomas Matthews Oct 16 '19 at 20:40
BTW, when `std::cin >> EUR_GBP` processes something that is not a floating point number, the stream will be in an error state. You should check the return value or the stream state. – Thomas Matthews Oct 16 '19 at 20:41

How do I reject inputs that are not numbers?

0 Answers0