Conversions Between Strings and Other Types
You can convert a numeric, Boolean, or date/time value to a String. You can also convert in the reverse direction — from a string value to numeric, Boolean, or Date — provided the contents of the string can be interpreted as a valid value of the destination data type. If they cannot, a run-time error occurs.
The conversions for all these assignments, in either direction, are narrowing conversions. You should use the type conversion keywords (CBool, CByte, CDate, CDbl, CDec, CInt, CLng, CSByte, CShort, CSng, CStr, CUInt, CULng, CUShort, and CType). The Format Function and Val Function give you additional control over conversions between strings and numbers.
If you have defined a class or structure, you can define type conversion operators between String and the type of your class or structure. For more information, see How to: Define a Conversion Operator.
Conversion of Numbers to Strings
You can use the Format function to convert a number to a formatted string, which can include not only the appropriate digits but also formatting symbols such as a currency sign (such as $), thousands separators or digit grouping symbols (such as ,), and a decimal separator (such as .). Format automatically uses the appropriate symbols according to the Regional Options settings specified in the Windows Control Panel.
Note that the concatenation (&) operator can convert a number to a string implicitly, as the following example shows.
' The following statement converts count to a String value.
Str = "The total count is " & count
Conversion of Strings to Numbers
You can use the Val function to explicitly convert the digits in a string to a number. Val reads the string until it encounters a character other than a digit, space, tab, line feed, or period. The sequences "&O" and "&H" alter the base of the number system and terminate the scanning. Until it stops reading, Val converts all appropriate characters to a numeric value. For example, the following statement returns the value 141.825.
Val(" 14 1.825 miles")
When Visual Basic converts a string to a numeric value, it uses the Regional Options settings specified in the Windows Control Panel to interpret the thousands separator, decimal separator, and currency symbol. This means that a conversion might succeed under one setting but not another. For example, "$14.20" is acceptable in the English (United States) locale but not in any French locale.
See Also
Tasks
How to: Convert an Object to Another Type in Visual Basic
Reference
Data Type Summary (Visual Basic)
Type Conversion Functions
Concepts
Widening and Narrowing Conversions
Implicit and Explicit Conversions
Value Changes During Conversions
Array Conversions
Introduction to International Applications Based on the .NET Framework