Decimals for numeric keypad

[vysero]

Hey guys. I am working on a numeric keypad which needs to handle decimal values. I am having some trouble handling decimal values in the range: [-1, 0, 1]. It would seem that when I convert a string of say 0. or 0.0 into a double the toDouble() function always spits out 0. This code works for values greater than 1 or less than -1:

        case Decimal:
      {
        if (m_maxDecimalDigits > 0)
        {
          digit = locale.decimalPoint();

          if (!value.contains(digit))
          {
            value.append(digit);
          }
        }
        break;
      }

Is there some way I can get the toDouble() method to convert a string of say: "0.0" into a number with a decimal such as 0.0?

[seeplus]

[Note this is C++/cli and NOT standard C++]

[JRManx]

You can convert it to a C-string and then use atof. You can't use standard type casting because it doesn't work with std::string objects.

This works:

std::string str {};
double num {};

char cstr[100] {};

std::cout << "Enter number. \n: ";
std::cin >> str;

// Convert str to a C-string
strcpy (cstr, str.c_str());

// And convert the C-string to a double.
num = atof (cstr);

std::cout << "Number: " << num << std::endl;

but it's somewhat cumbersome and complicated. If anyone has a better idea, feel free to spit it out!

Note: I tried reinterpret_cast and statis_cast, but those don't work. Neither does functional-style casting or c-style casting.

[seeplus]

a string of say: "0.0" into a number with a decimal such as 0.0?

A number is just a binary representation of the number. It has no concept of displaying a number. That is display.

As C++, is this what you're after?

#include <iostream>
#include <iomanip>
#include <sstream>
#include <string>

int main()
{
	double num {};
	std::string str;

	std::cout << "Enter number: ";
	std::cin >> str;

	std::istringstream iss(str);

	iss >> num;

	std::cout << std::fixed << std::setprecision(1) << num << '\n';
}

[Handy Andy]

Hello vysero,

You could also try this:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

#include <iostream> #include <iomanip> #include <string> int main() { double num {}; std::string str; std::cout << "Enter number: "; std::cin >> str; num = stod(str); std::cout << std::fixed << std::setprecision(8) << num << '\n'; }

Enter number: 1.12345678 1.12345678 Enter number: 0.12345678 0.12345678 Enter number: -1.12345678 -1.12345678

Andy