就业培训     下载中心     Wiki     联络 登录   注册
  1. 首页
  2. Qt 6.7.2
  3. Qt GUI
  4. C++ 类
  5. QDoubleValidator

QDoubleValidator 类

QDoubleValidator 类为浮点数提供范围校验。 更多...

头： #include <QDoubleValidator>
CMake: find_package(Qt6 REQUIRED COMPONENTS Gui)
target_link_libraries(mytarget PRIVATE Qt6::Gui)
qmake: QT += gui
继承： QValidator

公共类型

enum Notation { StandardNotation, ScientificNotation }

特性

公共函数

QDoubleValidator (QObject * parent = nullptr)
QDoubleValidator (double bottom , double top , int decimals , QObject * parent = nullptr)
virtual ~QDoubleValidator ()
double bottom () const
int decimals () const
QDoubleValidator::Notation notation () const
void setBottom (double)
void setDecimals (int)
void setNotation (QDoubleValidator::Notation)
void setRange (double minimum , double maximum , int decimals )
void setRange (double minimum , double maximum )
void setTop (double)
double top () const

重实现公共函数

(since 6.3) virtual void fixup (QString & input ) const override
virtual QValidator::State validate (QString & input , int & pos ) const override

信号

void bottomChanged (double bottom )
void decimalsChanged (int decimals )
void notationChanged (QDoubleValidator::Notation notation )
void topChanged (double top )

详细描述

QDoubleValidator provides an upper bound, a lower bound, and a limit on the number of digits after the decimal point.

You can set the acceptable range in one call with setRange (), or with setBottom () 和 setTop (). Set the number of decimal places with setDecimals ()。 validate () function returns the validation state.

QDoubleValidator uses its locale () to interpret the number. For example, in the German locale, "1,234" will be accepted as the fractional number 1.234. In Arabic locales, QDoubleValidator will accept Arabic digits.

注意： The QLocale::NumberOptions 设置在 locale () 还会影响数字的解释方式。例如，由于 QLocale::RejectGroupSeparator is not set by default (except on the "C" locale), the validator will accept group separators. If the string passes validation, pass it to locale ().toDouble() to obtain its numeric value.

另请参阅 QIntValidator , QRegularExpressionValidator , QLocale::toDouble ()，和 行编辑范例 .

成员类型文档编制

enum QDoubleValidator:: Notation

This enum defines the allowed notations for entering a double.

常量 值 描述
QDoubleValidator::StandardNotation 0 The string is written in the standard format, a whole number part optionally followed by a separator and fractional part, for example "0.015" .
QDoubleValidator::ScientificNotation 1 The string is written in scientific form, which optionally appends an exponent part to the standard format, for example "1.5E-2" .

The whole number part may, as usual, include a sign. This, along with the separators for fractional part, exponent and any digit-grouping, depend on locale. QDoubleValidator doesn't check the placement (which would also depend on locale) of any digit-grouping separators it finds, but it will reject input that contains them if QLocale::RejectGroupSeparator 有设置在 locale().numberOptions() .

另请参阅 QLocale::numberOptions (), QLocale::decimalPoint (), QLocale::exponential ()，和 QLocale::negativeSign ().

特性文档编制

bottom : double

This property holds the validator's minimum acceptable value

By default, this property contains a value of -infinity.

访问函数：

double bottom () const
void setBottom (double)

通知程序信号：

void bottomChanged (double bottom )

另请参阅 setRange ().

decimals : int

This property holds the validator's maximum number of digits after the decimal point

By default, this property contains a value of -1, which means any number of digits is accepted.

访问函数：

int decimals () const
void setDecimals (int)

通知程序信号：

void decimalsChanged (int decimals )

另请参阅 setRange ().

notation : Notation

This property holds the notation of how a string can describe a number

默认情况下，此特性被设为 ScientificNotation .

访问函数：

QDoubleValidator::Notation notation () const
void setNotation (QDoubleValidator::Notation)

通知程序信号：

void notationChanged (QDoubleValidator::Notation notation )

另请参阅 Notation .

top : double

This property holds the validator's maximum acceptable value

By default, this property contains a value of infinity.

访问函数：

double top () const
void setTop (double)

通知程序信号：

void topChanged (double top )

另请参阅 setRange ().

成员函数文档编制

[explicit] QDoubleValidator:: QDoubleValidator ( QObject * parent = nullptr)

Constructs a validator object with a parent object that accepts any double.

QDoubleValidator:: QDoubleValidator ( double bottom , double top , int decimals , QObject * parent = nullptr)

Constructs a validator object with a parent object. This validator will accept doubles from bottom to top inclusive, with up to decimals digits after the decimal point.

[virtual noexcept] QDoubleValidator:: ~QDoubleValidator ()

销毁验证器。

[override virtual, since 6.3] void QDoubleValidator:: fixup ( QString & input ) const

重实现： QValidator::fixup(QString &input) const .

这是重载函数。

Attempts to fix the input string to an Acceptable representation of a double.

The format of the number is determined by notation (), decimals (), locale () and the latter's numberOptions ().

To comply with notation (), when ScientificNotation is used, the fixed value will be represented in its normalized form, which means that any non-zero value will have one non-zero digit before the decimal point. 

QString input = "0.98765e2";
QDoubleValidator val;
val.setLocale(QLocale::C);
val.setNotation(QDoubleValidator::ScientificNotation);
val.fixup(input); // input == "9.8765e+01"

To comply with decimals (), when it is -1 the number of digits used will be determined by QLocale::FloatingPointShortest . Otherwise, the fractional part of the number is truncated (with rounding, as appropriate) if its length exceeds decimals (). When notation () 是 ScientificNotation this is done after the number has been put into its normalized form. 

input = "-1234.6789";
val.setDecimals(2);
val.setLocale(QLocale::C);
val.setNotation(QDoubleValidator::StandardNotation);
val.fixup(input); // input == "-1234.68"

注意： 若 decimals () is set to, and the string provides, more than std::numeric_limits<double>::digits10 , digits beyond that many in the fractional part may be changed. The resulting string shall encode the same floating-point number, when parsed to a double .

该函数在 Qt 6.3 引入。

void QDoubleValidator:: setRange ( double minimum , double maximum , int decimals )

Sets the validator to accept doubles from minimum to maximum inclusive, with at most decimals digits after the decimal point.

注意： Setting the number of decimals to -1 effectively sets it to unlimited. This is also the value used by a default-constructed validator.

void QDoubleValidator:: setRange ( double minimum , double maximum )

这是重载函数。

Sets the validator to accept doubles from minimum to maximum inclusive without changing the number of digits after the decimal point.

[override virtual] QValidator::State QDoubleValidator:: validate ( QString & input , int & pos ) const

重实现： QValidator::validate(QString &input, int &pos) const .

返回 Acceptable 若字符串 input is in the correct format and contains a double within the valid range.

返回 中间体 if input is in the wrong format or contains a double outside the range.

返回 Invalid 若 input doesn't represent a double or has too many digits after the decimal point.

Note: If the valid range consists of just positive doubles (e.g. 0.0 to 100.0) and input is a negative double then Invalid 被返回。若 notation () 被设为 StandardNotation , and the input contains more digits before the decimal point than a double in the valid range may have, Invalid 被返回。若 notation () 是 ScientificNotation , and the input is not in the valid range, 中间体 is returned. The value may yet become valid by changing the exponent.

默认情况下， pos 参数并未用于此验证器。

内容