C++'s equivalent of Java's Integer.parseInt()?

[Cobra220]

Sadly, I've been searching a couple hours for a one line way to parse strings into integers. It is such a ridiculously simple task that I'm almost hesitant to post this. Please keep the terminology at a low level as I am extremely new to this language.

Thanks guys!
-David

 

[cpjust]

Try a stringstream.

#include <sstream>
#include <iostream>

using namespace std;

int main()
{
   stringstream str;
   str << "666";   // Put the number into the stringstream.
   cout << "The number as a string: " << str.str() << endl;
   int num;
   str >> num;   // Move the number into an int.
   cout << "The number as an int: " << num << endl;
   str << "3.14";
   float pi;
   str >> pi;
   cout << "How about some pi? " << pi << endl;

   return 0;
}

 

[Cobra220]

In my program, I can't use stringstream or the >>/<< without getting errors. Do I have to be working in main to use these? Right now, I'm working on a form application. Here's what should happen: When a button is clicked, I read in text from a field, take a substring of it, and then parse that substring to an int, which I use later in the program.
Does this clarification help?

 

[cpjust]

Most of the Windows API uses WCHAR based strings, so maybe you need to use wstringstream instead of stringstream?

If you like living dangerously, you could also use a C function like sscanf() (or swscanf() for wide strings).

What compiler are you using and what are the error messages?

 

[Salem]

> In my program, I can't use stringstream or the >>/<< without getting errors.
Post
- your program
- your errors
- your OS/Compiler



--

 

[Cobra220]

I'm using Visual C++ '05 on Windows XP. Here is the code:

private: System::Void submitButton_Click(System::Object^  sender, System::EventArgs^  e)
		 {
			 String^a = serialField->Text; //from textfield
			 int c = 0;
			 String^b = a->Substring(1,8);
			 //parse String b into int c...how?
		 }

What I've got here works. I just get errors when I try different ways of parsing. I don't know too much about namespaces or included 'things' so I'll post what I do have:

	using namespace std;
	using namespace System;
	using namespace System::ComponentModel;
	using namespace System::Collections;
	using namespace System::Windows::Forms;
	using namespace System::Data;
	using namespace System::Drawing;

They're were all added automatically by Vis. C++. I didn't include any other stuff at the top.

Sorry for the lack of proper terminology and thanks for the help!
-David

 

[cpjust]

Aha! No wonder you're having problems. You're using Microsoft's bastardized version of "Managed" C++. I know nothing about that since it's an unholy sub-language of C++, but after looking on the MSDN site I think you want to use one of the Convert functions:

http://msdn.microsoft.com/library/d...s/cpref/html/frlrfsystemconvertclasstopic.asp

 

[Cobra220]

Thanks for that link. I've searched that page for some of my other questions/problems but never thought to lookup how to parse under convert.

In case anyone is interested, the following code is what worked for me:

try{
					 c = Convert::ToInt32(b);
				 }
				 catch(OverflowException^g){
					 Console::WriteLine("Overflow in Double to Int32 conversion");
				 }
				 catch(ArgumentNullException^g){
					 Console::WriteLine("String is null");
				 }
				 catch(FormatException^g){
					 Console::WriteLine("String does not consist of an optional sign followed by a series of digits");
				 }