Campbell-scientific CR9000X Measurement and Control System Uživatelský manuál stáhnout pdf (Strana 164)

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Section 4. CRBasic – Native Language Programming

4.2.11.3 Expressions with Numeric Data Types

FLOATs, LONGs and Booleans are cross-converted to other data types, such as

FP2, by using “=”

4.2.11.3.1 Boolean from FLOAT or LONG

When a FLOAT or LONG is converted to a Boolean as shown in EXAMPLE

4.0-2, zero becomes False (0) and non-zero becomes True (-1).

EXAMPLE 4.0-2. CRBASIC Code: Conversion of FLOAT / LONG to

Boolean

Public Fa AS FLOAT, Fb AS FLOAT, L AS LONG

Public Ba AS Boolean, Bb AS Boolean, Bc AS Boolean

BeginProg

Fa = 0

Fb = 0.125

L = 126

Ba = Fa ‘This will set Ba = False (0)

Bb = Fb ‘This will Set Bb = True (-1)

Bc = L ‘This will Set Bc = True (-1)

EndProg

4.2.11.3.2 FLOAT from LONG or Boolean

When a LONG or Boolean is converted to FLOAT, the integer value is loaded

into the FLOAT. Booleans will be converted to -1 or 0 depending on whether

the value is non-zero or zero. LONG integers greater than 24 bits (16,777,215;

the size of the mantissa for a FLOAT) will lose resolution when converted to

FLOAT.

4.2.11.3.3 LONG from FLOAT or Boolean

Booleans will be converted to -1 or 0. When a FLOAT is converted to a

LONG, it is truncated. This conversion is the same as the INT function. The

conversion is to an integer equal to or less than the value of the float (e.g., 4.6

becomes 4, -4.6 becomes -5).

If a FLOAT is greater than the largest allowable LONG (+2,147,483,647), the

integer is set to the maximum. If a FLOAT is less than the smallest allowable

LONG (-2,147,483,648), the integer is set to the minimum.

4.2.11.3.4 Integers in Expressions

LONGs are evaluated in expressions as integers when possible. Example

4.2.11-3 illustrates evaluation of integers as LONGs and FLOATs.

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