display->text().toDouble();中的display是什么意思
时间: 2023-07-15 13:10:58 浏览: 42
`display` 是一个对象或变量,它代表用户界面上的一个文本显示控件,例如一个标签或文本框。`text()` 是该控件的一个方法,用于获取当前显示在控件上的文本内容。`toDouble()` 是把获取到的文本内容转换为双精度浮点数类型的方法。因此,`display->text().toDouble()` 表示获取名为 `display` 的控件上当前显示的文本内容,并将其转换为双精度浮点数类型。
相关问题
Q21: Which of the following is a valid user-defined output stream manipulator header? a. ostream& tab( ostream& output ) b. ostream tab( ostream output ) c. istream& tab( istream output ) d. void tab( ostream& output ) Q22: What will be output by the following statement? cout << showpoint << setprecision(4) << 11.0 << endl; a. 11 b. 11.0 c. 11.00 d. 11.000 Q23: Which of the following stream manipulators causes an outputted number’s sign to be left justified, its magnitude to be right justified and the center space to be filled with fill characters? a. left b. right c. internal d. showpos Q24: Which of the following statements restores the default fill character? a. cout.defaultFill(); b. cout.fill(); c. cout.fill( 0 ); d. cout.fill( ' ' ); Q25: When the showbase flag is set: a. The base of a number precedes it in brackets. b. Decimal numbers are not output any differently. c. "oct" or "hex" will be displayed in the output stream. d. Octal numbers can appear in one of two ways. Q26: What will be output by the following statements? double x = .0012345; cout << fixed << x << endl; cout << scientific << x << endl; a. 1.234500e-003 0.001235 b. 1.23450e-003 0.00123450 c. .001235 1.234500e-003 d. 0.00123450 1.23450e-003 Q27: Which of the following outputs does not guarantee that the uppercase flag has been set? a. All hexadecimal numbers appear in the form 0X87. b. All numbers written in scientific notation appear the form 6.45E+010. c. All text outputs appear in the form SAMPLE OUTPUT. d. All hexadecimal numbers appear in the form AF6. Q28: Which of the following is not true about bool values and how they're output with the output stream? a. The old style of representing true/false values used -1 to indicate false and 1 to indicate true. b. A bool value outputs as 0 or 1 by default. c. Stream manipulator boolalpha sets the output stream to display bool values as the strings "true" and "false". d. Both boolalpha and noboolalpha are “sticky” settings.
A21: a. ostream& tab( ostream& output ) is a valid user-defined output stream manipulator header.
A22: c. 11.00 will be output by the statement.
A23: c. internal is the stream manipulator that causes an outputted number’s sign to be left justified, its magnitude to be right justified and the center space to be filled with fill characters.
A24: d. cout.fill(' ') restores the default fill character, which is a space.
A25: c. "oct" or "hex" will be displayed in the output stream when the showbase flag is set.
A26: b. 1.23450e-003 and 1.23450e-003 will be output by the statements.
A27: d. All hexadecimal numbers appearing in the form AF6 does not guarantee that the uppercase flag has been set.
A28: a. The old style of representing true/false values used -1 to indicate false and 1 to indicate true is not true. False is represented by 0 and true is represented by any non-zero value.
string json = File.ReadAllText("tsconfig1.json"); dynamic jsonObj = JsonConvert.DeserializeObject(json); dShutterValue = jsonObj["exposureTime"]; m_txt_Shutter.Text = dShutterValue.ToString("F2"); m_listCCamerInfo[m_nOperateID].m_objIGXFeatureControl.GetFloatFeature("ExposureTime").SetValue(dShutterValue); m_txt_Shutter.Clear(); try { if (!m_listCCamerInfo[m_nOperateID].m_bIsOpen) { return; } strValue = m_listCCamerInfo[m_nOperateID].m_objIGXFeatureControl.GetFloatFeature("ExposureTime").GetValue().ToString(); //浮点转字符串 dShutterValue = Convert.ToDouble(m_txt_Shutter.Text); 怎么改错System.FormatException:“输入字符串的格式不正确。”
System.FormatException: The format of the input string is incorrect.
The error occurs because the `Convert.ToDouble()` method is unable to parse the value in `m_txt_Shutter.Text` as a valid double. To fix this error, you can add error handling to handle cases where the input string cannot be converted to a double.
Here is an updated version of the code with error handling:
```csharp
try
{
if (!m_listCCamerInfo[m_nOperateID].m_bIsOpen)
{
return;
}
if (double.TryParse(m_txt_Shutter.Text, out dShutterValue))
{
m_listCCamerInfo[m_nOperateID].m_objIGXFeatureControl.GetFloatFeature("ExposureTime").SetValue(dShutterValue);
strValue = dShutterValue.ToString("F2");
}
else
{
// Handle invalid input here
// For example, display an error message or set a default value
}
}
catch (Exception ex)
{
// Handle any other exceptions here
// Log the exception or display an error message
}
```
In this code, `double.TryParse()` is used to attempt to parse the input string as a double. If the parsing is successful, the `dShutterValue` will be assigned the parsed value, and you can proceed with setting the value and converting it to a formatted string. If the parsing fails, you can handle the invalid input case as needed.
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