Campbell-scientific CR9000X Measurement and Control System Manual de usuario descargar pdf (Pagina 397)

Section 11. String Functions

11.1 Expressions with Strings

11.1.1 Constant Strings

Fixed (constant) strings can be used in expressions using quotation marks “”.

For example, FirstName = “Mike” causes the string variable FirstName to be

assigned “Mike”.

11.1.2 Add Strings

Strings can be concatenated using the ‘+’ operator or the ‘&’ operator.

If you need to concatenate strings and variables, use the ‘+’ operator.

When using the ‘&’ operator, the values being concatenated must be strings

(integers will be converted to strings). When working strictly with strings the

‘&’ operator can be safer to use than the ‘+’ operator, because with the ‘&’

operator there is no danger of a value being converted from a string to an

integer.

Example FullName = FirstName + “ “ + MiddleName + “ “ + LastName

FullName = FirstName & “ “ & MiddleName & “ “ & LastName

(The “ “ puts a space between the names.)

11.1.3 Subtraction of Strings

String1-String2 results in an integer in the range of –255..+255. Starting with

the first character in each string, the characters in string2 is subtracted from the

character in string1 until the difference is non-zero or until the end of each

string is reached. This is mainly used to determine if the strings are the same

or not.

11.1.4 String Conversion to/from Numeric

Conversion of Strings to Numeric and Numeric to Strings is done

automatically when an assignment is made from a string to a numeric or a

numeric to a string, if possible.

For example:

Public Value ‘ default, a IEEE4 float

Public SensorString AS String * 8 ‘an ASCII reading from a sensor

Value = SensorString * 1.8 + 32 ‘Sensor string is converted to the IEEE4

Value and scaled from Celsius to Fahrenheit.

11-1

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Campbell-scientific CR9000X Measurement and Control System Manual de usuario Pagina 397