How to convert one data type to another

Question

I am a very novice VB.NET programmer. How do I convert one type to another?

Dim a as String="2"
Dim b as Integer='what?

http://stackoverflow.com/questions/7708838/how-do-i-convert-from-a-string-to-an-integer-in-visual-basic — Janez Lukan, Nov 03 '13 at 17:36

score 1 · Answer 1 · answered Nov 03 '13 at 17:35

1

Many of the "primitive" data types have several parsing methods that can construct from a string representation.

Check the Parse and TryParse shared methods of Integer.

answered Nov 03 '13 at 17:35

Oded

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What about from any type? Like the `Convert` class in C#. – lost_in_the_source Nov 03 '13 at 17:37
@EdwardKarak - `Convert` most certainly doesn't handle **any** type. It is coded for specific, common, usages. There is no way to simply convert between any two unknown types. – Oded Nov 03 '13 at 17:38
2

@EdwardKarak The System.Convert class comes from the framework, not from C#, so it is the same in VB.NET. – Andrew Morton Nov 03 '13 at 17:43

score 1 · Accepted Answer · edited May 23 '17 at 11:45

There are several ways to convert a string to an integer.

You know the string contains a numeric:
```
Dim b as Integer = Integer.Parse(a) 
```
If it is not a valid integer or contains non numerals, it can crash. Other value types (Decimal, Double) have the same method.
Pretty much the same:
```
Dim b as Integer= Convert.ToInt32(b) 
```
You dont know if the string is clean or not. For instance this would be used to convert a value from a text box, where the user types "cat" as their age:
```
If Integer.TryParse(a, b) Then ...
```

The big difference here is that the return is a Boolean (True or False) telling you whether the parsing went ok. If not (False), tell the user to enter again; else (True) the second param will be the converted value. Date, Double, Decimal etc all have a TryParse method.

This answer provides a more detailed explanation.

How to convert one data type to another

2 Answers2

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