Converting Numbers

Before trying to convert a string to a number it is a good idea to always make sure that the value is a numerical value.
The ISNUMERIC function will return True or False depending if the value can be evaluated as a number.

String to Integer

The CINT function converts a String to an Integer data type.

Dim sMyString As String 
sMyString = "200" 
Dim iMyInteger As Integer 
If (IsNumeric(sMyString) = True) Then 
   iMyInteger = CInt(sMyString) 
End If 

String to Long

The CLNG function converts a String to a Long data type.

Dim sMyString As String 
sMyString = "200" 
Dim lMyLong As Long 
lMyLong = CLng(sMyString) 

String to Single

The CSNG function converts a String to a Single data type.

Dim sMyString As String 
sMyString = "34.5" 
Dim sngMySingle As Single 
sngMySingle = CSng(sMyString) 

String to Double

The CDBL function converts a String to a Double data type.

Dim sMyString As String 
sMyString = "34.5" 
Dim dbMyDouble As Double 
dbMyDouble = CDbl(sMyString) 

String to Decimal

The CDEC function converts a String to a Decimal data type.

Dim sMyString As String 
sMyString = "34.5" 
Dim dcMyDecimal As Variant 
dcMyDecimal = CDec(sMyString) 

Decimal to Integer

When you convert a Decimal value to a Long integer value it gets rounded to the nearest integer value.
Digits less than 5 are rounded down
Digits greater than 5 are rounded up
If the digit is 5, then it looks at the digit immediately before the decimal place
1) if its even, its rounded down
2) if its odd, its rounded up
3) if there is no digit, its rounded down
CLng(8.5) = 8 (because 8 is even)
CLng(9.5) - 10 (because 9 is odd)

Dim vdDecimal As Variant 
vdMyDecimal = 34.5 
Dim iMyInteger 
iMyInteger = CInt(vdMyDecimal) 

Number to String

The CSTR function converts a Number to a String data type.

Dim sMyString As String 
Dim lNumber As Long 
lNumber = 400 
sMyString = CStr(lNumber) 
Debug.Print "My String is " + sMyString 

More info Data Types > Converting
More info Numbers > Fixed Point
More info Numbers > Floating Point