TextBox: Conversion from String to Double - Managed C++/CLI Discussion Boards

sajjy30-Nov-08 10:19

30-Nov-08 10:19

Hi yesterday I was trying to build a program but i had a problem ...!
the problem was that when I put space (" ") in the string, it finishes the string aoutomatically , so what canI do to fix the problem?

notice that i cant use a array of characters in that solution Wink | ;)

Re: space in a string !

Mark Salsbery30-Nov-08 14:31

Mark Salsbery

30-Nov-08 14:31

sajjy wrote:
the problem was that when I put space (" ") in the string, it finishes the string aoutomatically

How? Some sample code would help! Smile | :)

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: space in a string !

led mike2-Dec-08 4:31

led mike

2-Dec-08 4:31

Mark Salsbery wrote:
How?

Probably using the space in his head. Smile | :)

led mike

Re: space in a string !

Mark Salsbery2-Dec-08 6:16

Mark Salsbery

2-Dec-08 6:16

Space....the final frontier....

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: space in a string !

led mike2-Dec-08 6:49

led mike

2-Dec-08 6:49

Mark Salsbery wrote:
Space....the final frontier

We kunt do it kaptin, we just dunt have the power!

led mike

Re: space in a string !

Paul Conrad2-Dec-08 6:57

Paul Conrad

2-Dec-08 6:57

"The clue train passed his station without stopping." - John Simmons / outlaw programmer

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

"Not only do you continue to babble nonsense, you can't even correctly remember the nonsense you babbled just minutes ago." - Rob Graham

Re: space in a string !

Paul Conrad30-Nov-08 18:00

Paul Conrad

30-Nov-08 18:00

sajjy wrote:
the problem was that when I put space (" ") in the string, it finishes the string aoutomatically

Huh? As Mark suggested, please provide a snippet of the code that is causing this problem.

TextBox: Conversion from String to Double

J_E_D_I25-Nov-08 9:31

J_E_D_I

25-Nov-08 9:31

Hi, I am new to CLI-Windows Forms programming and I need to perform this simple task:

1) Allow the user to enter a value in a Text Box (textBox1)
2) Assign such value to a variable of type double (variable1)
[I am having difficulties casting the string to double]
3) Perform computations on that variable
[I should be able to do this once it's a double]
4) Display the resulting value in another Text Box (textBox2)

Can someone be so kind to help me with the correct syntax I should use for each step?
Many thanks.

Re: TextBox: Conversion from String to Double

Mark Salsbery25-Nov-08 11:51

Mark Salsbery

25-Nov-08 11:51

For step 2:

Double.Parse Method[^]
Double.TryParse Method[^]

For step 4:

Double.ToString Method[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: TextBox: Conversion from String to Double

J_E_D_I26-Nov-08 2:00

J_E_D_I

26-Nov-08 2:00

Thanks for the advice, it works. But I obviously get a crash when I leave the text box empty or I enter a non numerical value.

Here is the code I use to assign the value entered in the text box (as string) to a type double variable:

//
variable1 = double::Parse(textBox1->Text);
//

How can I solve this? Thanks!

Re: TextBox: Conversion from String to Double

Mark Salsbery26-Nov-08 4:56

Mark Salsbery

26-Nov-08 4:56

J_E_D_I wrote:
But I obviously get a crash when I leave the text box empty or I enter a non numerical value.

Use TryParse().

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: TextBox: Conversion from String to Double

J_E_D_I26-Nov-08 7:57

J_E_D_I

26-Nov-08 7:57

I have tried:
//
double number;
variable1 = double::TryParse(textBox1->Text, number);
//

With the code above it's better and the program does not crash anymore.
However the problem is not completely solved because when I leave the text box empty or enter a character different from a number, the result of variable1 is zero, which causes an error in the calculation that follows.

How can I show an "Error" message when this has happened?
Alternatively, is there any way that I could make the textBox accept only numerical values and display an error in the other cases?

Re: TextBox: Conversion from String to Double

Mark Salsbery26-Nov-08 8:12

Mark Salsbery

26-Nov-08 8:12

TryParse returns a bool.

double variable1;
if (double::TryParse(textBox1->Text, variable1))
{
    // parse succeeded - safe to use use variable1
}
else
{
    // parse failed
}

Did your Visual Studio not come with MSDN library? Smile | :)

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: TextBox: Conversion from String to Double

J_E_D_I26-Nov-08 8:44

J_E_D_I

26-Nov-08 8:44

This is a fantastic answer! Thank you so much, it solved the problem.

Mark Salsbery wrote:
Did your Visual Studio not come with MSDN library?

Probably you guys super expert programmers manage to find what you are looking for in MSDN. I program in my spare time just for fun and I do not find them helpful AT ALL!! Sigh | :sigh:

They seriously lack of simple examples for beginners like me and they take too much for granted. Regarding TryParse there was no specific example for c++.

Cheers!

Re: TextBox: Conversion from String to Double

Mark Salsbery26-Nov-08 10:32

Mark Salsbery

26-Nov-08 10:32

J_E_D_I wrote:
there was no specific example for c++

Hint: Use the C# examples. For most examples of using .NET framework classes, the only
difference will be

'->' in c++ instead of '.' in c#
gcnew in c++ instead of new in c#.

Cheers! Beer | [beer]

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: TextBox: Conversion from String to Double

led mike25-Nov-08 11:52

led mike

25-Nov-08 11:52

J_E_D_I wrote:
Hi, I am new to CLI-Windows Forms programming and I need to perform this simple task:

See if this helps[^]

led mike

Re: TextBox: Conversion from String to Double

Mark Salsbery25-Nov-08 12:36

Mark Salsbery

25-Nov-08 12:36

Awesome!

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: TextBox: Conversion from String to Double

led mike26-Nov-08 7:19

led mike

26-Nov-08 7:19

Mark Salsbery wrote:
Awesome!

Nah, that was mildly amusing. This is awesome.[^]

led mike

Re: TextBox: Conversion from String to Double

Mark Salsbery26-Nov-08 8:13

Mark Salsbery

26-Nov-08 8:13

Indeed!

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

How to set an Integer value to System::String ^

niiAmoo21-Nov-08 20:50

niiAmoo

21-Nov-08 20:50

Hi,

I am new to Visual C++/.Net, I have a simple question. I have a DateTimePicker object which I need to display future date in days (i.e. if you pick 11/21/2009, I will display 365 days).

I have managed to compute my 365 days and converted it to a char * but I am not able to assign the char* to the label Text i.e. Sysytem::String ^

Can anyone help me? Thanks in advance

Re: How to set an Integer value to System::String ^

Christian Graus21-Nov-08 21:25

Christian Graus

21-Nov-08 21:25

If you have a number, just call ToString() to get a System::String^

Christian Graus

Driven to the arms of OSX by Vista.

Re: How to set an Integer value to System::String ^

Mark Salsbery22-Nov-08 6:24

Mark Salsbery

22-Nov-08 6:24

niiAmoo wrote:
I have managed to compute my 365 days and converted it to a char *

Why are you using char * in C++/CLI?

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: How to set an Integer value to System::String ^

niiAmoo22-Nov-08 7:32

niiAmoo

22-Nov-08 7:32

Sorry, That was what I was used to Frown | :-(

. I tried this code and it worked

TimeSpan expirationDay = expirationDateTimePicker->Value.Date - expirationDateTimePicker->Value.Now.Date;
expiration->Text = expirationDay.Days.ToString();

Thanks for your help

Re: How to set an Integer value to System::String ^

Luc Pattyn22-Nov-08 9:35