And

From Xojo Documentation

Operator

Used to perform a logical comparison of two boolean expressions and a bitwise And comparison of two integer expressions.

Usage

result = expression1 And expression2

Part Description
result A Boolean if expression1 and expression2 are booleans; an integer if expression1 and expression2 are integers.
expression1 Any valid boolean or integer expression. The data types of expression1 and expression2 must match.
expression2 Any valid boolean or integer expression. The data types of expression1 and expression2 must match.

Notes

The And operator is overloaded. You can pass either two booleans or two integers. If you pass two booleans, And performs a logical And operation and returns a boolean. If you pass two integers, it performs a bitwise And operation and returns an integer. In this case, it is equivalent to calling the BitAnd method of the Bitwise class.

In the first instance, if both boolean expressions evaluate to True, then result is True. If either expression evaluates to False then result is False.

The truth table for logical operators is shown below.

Boolean Comparison
Expression1 Expression2 And Or Xor
True True True True False
True False False True True
False True False True True
False False False False False

If you pass two integers, And returns an integer that is the result of comparing each bit of the two integers and assigning 1 to the bit position in the integer returned if both bits in the same position in the integers passed are 1. Otherwise, 0 is assigned to the bit position.

The following table gives the results for bitwise operators.

Bitwise Comparison
Integer1 Integer2 And Or Xor
0 0 0 0 0
0 1 0 1 1
1 0 0 1 1
1 1 1 1 0

The Operator_And function can be used to define the And operator for classes.

Use within If Statements

When used within an If..Then statement, once the first expression results to False, none of the subsequent expressions are evaluated. In this example, the IsValid method is not called because the first expression is False. This is referred to as short-circuit evaluation:

Dim b As Boolean = False
If b And IsValid("value") Then // IsValid does not get called
...
End If

Sample Code

This example uses the And operator to perform logical comparisons.

Dim a As Boolean
Dim b As Boolean
Dim c As Boolean // defaults to False
Dim d As Boolean // defaults to False

a = True
b = True
d = a And b // Returns True
d = a And c // Returns False

Using And with Integer values:

Dim i1 As Integer = 4
Dim i2 As Integer = 5

Dim result As Integer
result = i1 And i2 // result = 4

To understand how the above evaluates to 4, look at the binary values. The value of 4 is "100" in binary. The value of 5 is "101" binary. If you "And" those two binary values together then only the first "1" is in common. So the result is "100", which is 4.

See Also

Not, Or, Xor operators; Bitwise class; Operator_And function; Operator precedence