Teledyne-lecroy Protocol Analyzers File-Based Decoding User Manual Uživatelský manuál stáhnout pdf (Strana 13)

File-based Decoding User Manual Chapter 3: Expressions

LeCroy Corporation 7

Chapter 3: Expressions

An expression is a statement that calculates a value. The simplest type of expression is

assignment:

x = 2

The expression x = 2 calculates 2 as the value of x.

All expressions contain operators, which are described in

Chapter 4, Operators, on page 9. The operators indicate how an expression should be

evaluated in order to arrive at its value. For example

x + 2

says to add 2 to x to find the value of the expression. Another example is

x > 2

which indicates that x is greater than 2. This is a Boolean expression, so it evaluates to

either true or false. Therefore, if

x = 3, then x > 2 evaluates to true; if x = 1, it returns

false.

True is denoted by a non-zero integer (any integer except 0), and false is a zero integer

(0). True and false are also supported for lists (an empty list is false, while all others are

true), and strings (an empty string is false, while all others are true), and

null is

considered false. However, all Boolean operators result in integer values.

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Teledyne-lecroy Protocol Analyzers File-Based Decoding User Manual Uživatelský manuál Strana 13