Metodo Conversion.Val (String)

 

Restituisce i numeri contenuti in una stringa come valore numerico del tipo appropriato.

Spazio dei nomi:   Microsoft.VisualBasic
Assembly:  Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)

public static double Val(
	string InputStr
)

Parametri

InputStr
Type: System.String

Obbligatorio. Qualsiasi espressione String, variabile Object o valore Char valido. Se Expression è di tipo Object, il valore deve essere convertibile in String o si verifica un errore ArgumentException.

Valore restituito

Type: System.Double

Restituisce i numeri contenuti in una stringa come valore numerico del tipo appropriato.

Exception Condition
OverflowException

InputStr è troppo grande.

ArgumentException

Expression è un'espressione di tipo Object che non è convertibile in String.

The Val function stops reading the string at the first character it cannot recognize as part of a number. Symbols and characters that are often considered parts of numeric values, such as dollar signs and commas, are not recognized. However, the function recognizes the radix prefixes &O (for octal) and &H (for hexadecimal). Blanks, tabs, and linefeed characters are removed from the argument.

The following call returns the value 1234123.


Val(" 1234 123th Street N.E.") 

The following call returns the decimal value -1.


Val("&HFFFF") 
System_CAPS_noteNota

The Val function recognizes only the period (.) as a valid decimal separator. When other decimal separators are used, as in international applications, use CDbl or CInt instead to convert a string to a number. To convert the string representation of a number in a particular culture to a numeric value, use the numeric type's Parse(String, IFormatProvider) method. For example, use M:System.Double.Parse(System.String,System.IFormatProvider) when converting a string to a Double.

System_CAPS_noteNota

An T:System.InvalidCastException exception might be raised in response to certain uncommon number formats. For example, the following code raises this exception.

' These examples cause run-time errors.

'Console.WriteLine(Val("1.34%"))

'Console.WriteLine(Val("1.34&"))

The conflict between the number formatted as a Double and the Integer and Long type characters would be caught by the compiler if the conflict were not contained in strings.

' These examples cause compiler errors.

'Dim m = 1.34%

'Dim n = 1.34&

The following example uses the Val function to return the numbers contained in each string. Val stops converting at the first character that cannot be interpreted as a numeric digit, numeric modifier, numeric punctuation, or white space.

Dim valResult As Double
' The following line of code sets valResult to 2457.
valResult = Val("2457")
' The following line of code sets valResult to 2457.
valResult = Val(" 2 45 7")
' The following line of code sets valResult to 24.
valResult = Val("24 and 57")

.NET Framework
Disponibile da 1.1
Silverlight
Disponibile da 2.0
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