Converting a string using the Double.TryParse method in C#

Question

Right now, I converted all 3 strings into an int, but I'm having trouble converting each string using the Double.TryParse method. I want to use that method instead of int.

I tried using this type of code if (Double.TryParse(value, out number)), but I'm not to sure exactly if this is right.

//Ask the user for height
Console.Write("Please enter the first part of your height in feet:");
string _height = Console.ReadLine();
int _heightVal = Int32.Parse(_height);

//Ask the user for inches
Console.Write("Please enter the second part of your height in inches:");
string _inches = Console.ReadLine();
int _inchesVal = Int32.Parse(_inches);

//Ask the user for pounds
Console.Write("Please enter your weight in pounds:");
string _pounds = Console.ReadLine();
int _poundsVal = Int32.Parse(_pounds);

tryparse should be wrapped in an if where you somehow deal with the failure. learn.microsoft.com/en-us/dotnet/api/… — Steve Greene
– Steve Greene, Commented Apr 4, 2019 at 16:49
Double seems like a bad choice for feet and inches. Maybe for weight, but if it is fractional perhaps use decimal. — Steve Greene
– Steve Greene, Commented Apr 4, 2019 at 16:53

Ashkan Mobayen Khiabani · Accepted Answer · 2019-04-04 16:56:02Z

11

double heightVal = 0;
double.TryParse(_height, out heightVal);

heightVal will have the value of the Parse from _height if Parsing is successful, otherwise it will have the it's previous value (0 in here)

TryParse() returns a boolean indicating if the Parsing was successful that you can use it like:

bool success = double.TryParse(_height, out heightVal);

or

if(double.TryParse(_height, out heightVal))
{
     //Parse was successful and heightVal contains the new value
     // and you can use it in here
}

Fail Example:

double defaultValue = 0;
string str = "abc"
bool success = double.TryParse(str, defaultValue );

Output:

defaultValue = 0

success = false

Success Example:

double defaultValue = 0;
string str = "123"
bool success = double.TryParse(str, defaultValue );

Output:

defaultValue = 123

success = true

edited Apr 4, 2019 at 16:56

answered Apr 4, 2019 at 16:48

Ashkan Mobayen Khiabani

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2 Comments

Jonathon Chase Over a year ago

Might want to add an example that utilizes the returned boolean.

Ashkan Mobayen Khiabani Over a year ago

@JonathonChase I'm doing it ;)

Khaled Sameer · Accepted Answer · 2019-04-04 16:50:45Z

0

i think you just trying to force use enter the correct value you can use wile loop like this

 double userHeight = 0.0;
        while (true)
        { 
            //Ask the user for height
            Console.Write("Please enter the first part of your height in feet:");
            string _height = Console.ReadLine();
            if (Double.TryParse(_height, out double height))
            {
                userHeight = height;
                break;
            }

        }

then apply to all your questions

answered Apr 4, 2019 at 16:50

Khaled Sameer

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