将文本框字符串转换为float？ [英] Converting textbox string to float?

问题描述

我基本上试图在visual studio 2008中编写一个基本的转换器，我有两个文本框，一个从用户输入，一个给出输出结果。当我按下按钮时，我希望第一个文本框中的输入乘以4.35，然后显示在第二个文本框中。这是我的代码在按钮代码到目前为止：

  String ^ i1 = textBox1-& 
 float rez =（i1 * 4.35）ToString; 
 textBox2-> Text = rez;但是我得到这些错误：
 
  

f：\microsoft visual studio 9.0 \projects\hellowin\hellowin\Form1.h（148）：error C2676：binary'*'：'System :: String ^'不定义此运算符或转换为预定义运算符可接受的类型
f：\microsoft visual studio 9.0 \projects\hellowin\hellowin\Form1.h（148）：错误C2227： ' - > ToString'的左边必须指向类/ struct / union / generic类型
f：\microsoft visual studio 9.0 \projects\hellowin\hellowin\Form1.h（149）：error C2664 ：'void System :: Windows :: Forms :: Control :: Text :: set（System :: String ^）'：无法将参数1从'float'转换为'System :: String ^'


请帮助我疯狂地想从C ++中的文本框获取一些输入是多么可笑的困难。

解决方案

我已经找到了所有的错误，没有什么有用的东西，

为您修复它，

  String ^ i1 = textBox1-& 
 float rez =（float）（Convert :: ToDouble（i1）* 4.35）; 
 textBox2-> Text = rez.ToString（）; 
  

基本上，你想将字符串转换为实际数字，做数学，返回到显示目的的字符串。

I'm basically trying to write a basic converter in visual studio 2008, and I have 2 text boxes, one which gets input from the user, and one which gives output with the result. When I press the button I want the input from the first textbox to multiply by 4.35 then display in the 2nd textbox. This is my code in the button code so far:

             String^ i1 = textBox1->Text;
             float rez = (i1*4.35)ToString;
             textBox2->Text = rez;

However I'm getting these errors:

f:\microsoft visual studio 9.0\projects\hellowin\hellowin\Form1.h(148) : error C2676: binary '*' : 'System::String ^' does not define this operator or a conversion to a type acceptable to the predefined operator
f:\microsoft visual studio 9.0\projects\hellowin\hellowin\Form1.h(148) : error C2227: left of '->ToString' must point to class/struct/union/generic type
f:\microsoft visual studio 9.0\projects\hellowin\hellowin\Form1.h(149) : error C2664: 'void System::Windows::Forms::Control::Text::set(System::String ^)' : cannot convert parameter 1 from 'float' to 'System::String ^'

Please help I'm going insane on how ridiculously difficult it is to get some input from a textbox in C++. I've googled every error I had and nothing useful came up, I've been searching answers for an hour already, please help.

解决方案

Fixing it for you,

         String^ i1 = textBox1->Text;
         float rez = (float)(Convert::ToDouble(i1)*4.35);
         textBox2->Text = rez.ToString();

Basically, you want to convert your string to an actual number, do the math, and then make it back into a string for displaying purposes.

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