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3 string null character – Campbell Scientific CR3000 Micrologger User Manual

Page 243

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Section 7. Installation

243

 

Table 41. String Concatenation Examples

Expression Comments Result

Str(1) = 5.4 + 3 + " Volts"

Add floats, concatenate strings

"8.4 Volts"

Str(2) = 5.4 & 3 & " Volts"

Concatenate floats and strings

"5.43 Volts"

Lng(1) = "123"

Convert string to long

123

Lng(2) = 1+2+"3"

Add floats to string / convert to long

33

Lng(3) = "1"+2+3

Concatenate string and floats

123

Lng(4) = 1&2&"3"

Concatenate floats and string

123

 

7.8.13.3 String NULL Character

All strings are automatically NULL terminated. NULL, Chr(0) or "", counts as
one of the characters in the string. Assignment of just one character is that
character followed by a NULL, unless the character is a NULL.

Table 42. String NULL Character Examples

Expression Comments

Result

LongVar(5) = "#"-""

Subtract NULL, ASCII code results

35

LongVar(6) = StrComp("#","")

Also subtracts NULL

35

Example:

Objective:

Insert a NULL character into a string, and then reconstitute the string. 

Given:

StringVar(3) = "123456789"

Execute:

StringVar(3,1,4) = "" "12356789"

Results:

StringVar(4) = StringVar(3) "123"

But,

StringVar(3) still = "12356789",

so,

StringVar(5) = StringVar(3,1,4+1)
'"56789"
StringVar(6) = StringVar(3) + 4 + StringVar(3,1,4+1)
'"123456789"

Some smart sensors send strings containing NULL characters. To manipulate a
string that has NULL characters within it (in addition to being terminated with
another NULL), use MoveBytes() instruction.