TryParse()
OutputVar := MfFloat.TryParse(result, s)
OubputVar := MfFloat.TryParse(result, s, style[, provider ])
Tries to converts the s representation of a number to its MfFloat equivalent. A return value indicates whether the conversion succeeded.
result
Contains the value equivalent to the number contained in s, if the conversion succeeded.
The conversion fails if the s parameter is null or empty string, is not a number in a valid format, or represents a number less than MinValue or greater than MaxValue. This parameter is passed uninitialized; any value originally supplied in result will be overwritten.
s
An object to convert.
Can be var or instance of MfChar, MfString
Returns true if parse is a success; Otherwise false
Throws MfInvalidOperationException if not called as static method.
This overload differs from the MfFloat.Parse(s) method by returning a Boolean value that indicates whether the parse operation succeeded instead of returning the parsed numeric value. It eliminates the need to use exception handling to test for a MfFormatException in the event that s is invalid and cannot be successfully parsed.
The s parameter can contain the current culture's MfNumberFormatInfo.PositiveInfinitySymbol, MfNumberFormatInfo.NegativeInfinitySymbol, MfNumberFormatInfo.NaNSymbol, or a string of the form:
[ws][sign][integral-digits[,]]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]
Elements in square brackets ([ and ]) are optional. The following table describes each element.
Element |
Description |
ws |
A series of white-space characters. |
sign |
A negative sign symbol (-) or a positive sign symbol (+). Only a leading sign can be used. |
integral-digits |
A series of digits ranging from 0 to 9 that specify the integral part of the number. Runs of integral-digits can be partitioned by a group-separator symbol. For example, in some cultures a comma (,) separates groups of thousands. The integral-digits element can be absent if the string contains the fractional-digits element. |
, |
A culture-specific thousands separator symbol. |
. |
A culture-specific decimal point symbol. |
fractional-digits |
A series of digits ranging from 0 to 9 that specify the fractional part of the number. |
E |
The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation. |
exponential-digits |
A series of digits ranging from 0 to 9 that specify an exponent. |
The s parameter is interpreted using a combination of the MfNumberStyles.Float and MfNumberStyles.AllowThousands flags. This means that white space and thousands separators are allowed, for example, while currency symbols are not.
values := [ "1,643.57", "$1,643.57", "-1.643e6"
, "-168934617882109132", "123AE6"
,Null , "", "ABCDEF" ]
sb := new MfText.StringBuilder()
number := MfFloat
for i, value in values
{
if (MfFloat.TryParse(number, value))
{
sb.AppendFormat("'{0}' --> {1}", value, number.Value)
sb.AppendLine()
}
else
{
sb.AppendFormat("Unable to parse '{0}'.", value)
sb.AppendLine()
}
}
MsgBox % sb.ToString()
/*
'1,643.57' --> 1643.570000
Unable to parse '$1,643.57'.
'-1.643e6' --> -1643000.000000
'-168934617882109132' --> -168934617882108990.000000
Unable to parse '123AE6'.
Unable to parse ''.
Unable to parse ''.
Unable to parse 'ABCDEF'.
*/
Tries to converts the s representation of a number to its MfFloat equivalent. A return value indicates whether the conversion succeeded.
result
Contains the value equivalent to the number contained in s, if the conversion succeeded.
The conversion fails if the s parameter is null or empty string, is not a number in a valid format, or represents a number less than MinValue or greater than MaxValue. This parameter is passed uninitialized; any value originally supplied in result will be overwritten.
s
An string var of object convert.
Can be var or instance of MfChar, MfString
style
MfNumberStyles Instance or Integer var representing instance.
A bitwise combination of MfNumberStyles values that indicates the style elements that can be present in s. A typical value to specify is MfNumberStyles.Integer.
provider
An Optional object that supplies culture-specific parsing information about s. If provider is null, then MfNumberFormatInfo is used.
Returns true if parse is a success; Otherwise false
Throws MfInvalidOperationException if not called as static method.
Throws MfArgumentException style is not a MfNumberStyles value.
-or-
style includes MfNumberStyles.AllowHexSpecifier value.
The TryParse method is like the Parse(s, style, provider) method, except the TryParse method, except this method does not throw an exception if the conversion fails. If the conversion succeeds, the return value is true and the result parameter is set to the outcome of the conversion. If the conversion fails, the return value is false and the result parameter is set to zero. This eliminates the need to use exception handling to test for a MfFormatException in the event that s is invalid and cannot be successfully parsed.
The style parameter defines the style elements (such as white space, thousands separators, and currency symbols) that are allowed in the s parameter for the parse operation to succeed. It must be a combination of bit flags from the MfNumberStyles enumeration. The following MfNumberStyles members are not supported:
The s parameter can contain the current culture's MfNumberFormatInfo.PositiveInfinitySymbol, MfNumberFormatInfo.NegativeInfinitySymbol, or MfNumberFormatInfo.NaNSymbol. Depending on the value of style, it can also take the form:
[ws][$][sign][integral-digits[,]]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]
Elements in square brackets ([ and ]) are optional. The following table describes each element.
Element |
Description |
ws |
A series of white-space characters. White space can appear at the beginning of s if style includes the MfNumberStyles.AllowLeadingWhite flag, and it can appear at the end of s if style includes the MFNumberStyles.AllowTrailingWhite flag. |
$ |
A culture-specific currency symbol. Its position in the string is defined by the MfNumberFormatInfo.CurrencyNegativePattern and MfNumberFormatInfo.CurrencyPositivePattern properties of the current culture. The current culture's currency symbol can appear in s if style includes the MfNumberStyles.AllowCurrencySymbol flag. |
sign |
A negative sign symbol (-) or a positive sign symbol (+). The sign can appear at the beginning of s if style includes the MFNumberStyles.AllowLeadingSign flag, and it can appear at the end of s if style includes the MFNumberStyles.AllowTrailingSign flag. Parentheses can be used in s to indicate a negative value if style includes the MfNumberStyles.AllowParentheses flag. |
integral-digits |
A series of digits ranging from 0 to 9 that specify the integral part of the number. The integral-digits element can be absent if the string contains the fractional-digits element. |
, |
A culture-specific group separator. The current culture's group separator symbol can appear in s if style includes the MfNumberStyles.AllowThousands flag |
. |
A culture-specific decimal point symbol. The current culture's decimal point symbol can appear in s if style includes the MFNumberStyles.AllowDecimalPoint flag. |
fractional-digits |
A series of digits ranging from 0 to 9 that specify the fractional part of the number. Fractional digits can appear in s if style includes the MfNumberStyles.AllowDecimalPoint flag. |
E |
The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation. The s parameter can represent a number in exponential notation if style includes the MfNumberStyles.AllowExponent flag. |
exponential-digits |
A series of digits ranging from 0 to 9 that specify an exponent. |
A string with digits only (which corresponds to the MfNumberStyles.None style) always parses successfully. The remaining MfNumberStyles members control elements that may be present, but are not required to be present, in the input string. The following table indicates how individual MfNumberStyles flags affect the elements that may be present in s.
NumberStyles value |
Elements permitted in s in addition to digits |
The integral-digits element only. |
|
The decimal point (.) and fractional-digits elements. |
|
The "e" or "E" character, which indicates exponential notation. This flag by itself supports values in the form digitsEdigits; additional flags are needed to successfully parse strings with such elements as positive or negative signs and decimal point symbols. |
|
The ws element at the beginning of s. |
|
The ws element at the end of s. |
|
The sign element at the beginning of s. |
|
The sign element at the end of s. |
|
The sign element in the form of parentheses enclosing the numeric value. |
|
The thousands separator (,) element. |
|
The currency ($) element. |
|
All elements. However, s cannot represent a hexadecimal number or a number in exponential notation. |
|
The ws element at the beginning or end of s, sign at the beginning of s, and the decimal point (.) symbol. The s parameter can also use exponential notation. |
|
The ws, sign, thousands separator (,) and decimal point (.) elements. |
|
All elements. However, s cannot represent a hexadecimal number. |
The provider parameter is an MfFormatProvider implementation, such as a MFNumberFormatInfo object, whose GetFormat method returns a MFNumberFormatInfo object. The MFNumberFormatInfo object provides culture-specific information about the format of s.
Ordinarily, if you pass the MfFloat.Parse method a string that is created by calling the MfFloat.ToString method, the original Float value is returned. However, because of a loss of precision, the values may not be equal. In addition, attempting to parse the string representation of either MinValue or MaxValue results in NegativeInfinity and PostiveInfinity as the following example illustrates.
value := MfFloat.MinValue
wf := Mfunc.SetFormat(MfSetFormatNumberType.Instance.FloatFast, "0.16e")
result := value + 0.0
sb := new MfText.StringBuilder()
sb.AppendFormat("MinValue: {0}", result)
sb.AppendLine()
try
{
sb.AppendFormat("ParseResult: {0}", MfFloat.Parse(value))
sb.AppendLine()
}
catch e
{
sb.AppendLine()
sb.Append(e.ToString())
}
value := MfFloat.MaxValue
result := value + 0.0
sb.AppendFormat("MaxValue: {0}", result)
sb.AppendLine()
try
{
sb.AppendFormat("ParseResult: {0}", MfFloat.Parse(value))
}
catch e
{
sb.AppendLine()
sb.Append(e.ToString())
}
Mfunc.SetFormat(MfSetFormatNumberType.Instance.FloatFast, wf)
MsgBox % sb.ToString()
/*
MinValue: -1.7976931348623157e+308
ParseResult: -Infinity
MaxValue: 1.7976931348623157e+308
ParseResult: Infinity
*/
If a separator is encountered in the s parameter during a parse operation, and the applicable currency or number decimal and group separators are the same, the parse operation assumes that the separator is a decimal separator rather than a group separator. For more information about separators, see CurrencyDecimalSeparator, NumberDecimalSeparator, CurrencyGroupSeparator, and NumberGroupSeparator.