Vc#2005 Quick Start using Boolean operators

A Boolean operator (a Boolean operator) is an operator that evaluates to either true or false. C # provides several very useful Boolean operators, the simplest of which is the not (negation) operator, which uses an exclamation point (!). to indicate that.! the operator asks for a Boolean value of the inverse value. In the example above, if the variable Areyouready value is true, then the expression!areyouready evaluates to False.

Understanding equality and relational operators

The two more commonly used Boolean operators are equal (= =) and unequal (!=) operators. Using these two two-element operators, you can determine whether a value is equal to another value of the same type. Table 1 shows how these operators work, taking an int variable named age as an example.

Table 1 Boolean operators

operator	Meaning	Example	Result (assuming age = 42)
==	Equals	Age = = 100	False
!=	Not equal to	Age!= 0	True

Closely related to the above two operators is the relational operator (relational operator). Using these operators, you can determine whether a value is less than or greater than another value of the same type. Table 2 shows you how to use these operators.

Table 2 relational operators

operator	meaning	example	result (assuming age = N)
&<	less than	age &<	&<=		false
>		age >	& gt;=	is greater than or equal to	age >=	true

Be careful not to confuse the equality operator (= =) with the assignment operator (=). Code like x==y compares X and Y, and returns True if two values are the same. Instead, code like X=y assigns the value of Y to X.

Understanding Conditional logical operators

C # also provides two additional Boolean operators: the Logical AND (logical AND) operator, which is represented by &&, and the logical or (logical OR) operator, which uses the | | to indicate. These two operations Fu Shi called conditional logical operators (conditional logical operator). Their role is to combine different Boolean expressions to form a larger expression. The similarity between the two two-dollar operators and the equality and relational operators is that their results are true or false. The difference is that the value (operand) that they manipulate must itself be true or false.

The,&& operator evaluates to true only if the two Boolean expressions that are operands are true. For example, the following statement assigns a true value to validpercentage only if the value of the percent is greater than or equal to zero, and the percent value is less than or equal to 100:

BOOL Validpercentage;

Validpercentage = (Percent >= 0) && (Percent &<= 100);

A common mistake for beginners is to name the percent variable only once when merging two Tests, as follows:

Percent >= 0 && &<= 100//This statement cannot be compiled

Using parentheses helps to avoid this type of error and also helps clarify expressions. For example, you can compare the following two expressions:

Validpercentage = percent >= 0 && percent &<= 100

Validpercentage = (Percent >= 0) && (Percent &<= 100)