Rockwell-automation 1771-DB BASIC MODULE Uživatelský manuál stáhnout pdf (Strana 124)

100

101

Chapter

Expressions, Variables and Operators

9 -14

Two operators in the BASIC module can manipulate strings.

These operators are ASC and CHR.

ASC

Use the ASC operator to return the integer value of the ASCII character

placed in the parentheses.

The BASIC module capitalizes all ASCII characters. The decimal

representation for the ASCII character “A” is 65. The decimal

representation for the ASCII character “a” is 97. However the BASIC

module prints 65 for both characters.

REM EXAMPLE PROGRAM

10 PRINT ASC(a)

20 PRINT ASC(A)

READY

>RUN

READY

Do not use special ASCII characters with a decimal value greater than 127.

In addition, you can evaluate individual characters in a defined ASCII

string with the ASC operator. When you use the ASC operator, the $(expr)

denotes what string you want to access. The expression after the comma

selects an individual character in the string. In this example, the first

character in the string is selected. The decimal representation for the

ASCII character T is 84. String character position 0 is invalid.

STRING 1000,40

10 $(1) =“THIS IS A STRING”

20 PRINT $(1)

30 PRINT ASC($(1),1)

40 END

READY

>RUN

THIS IS A STRING

READY

String Operators

1 2 ... 119 120 121 122 123 124 125 126 127 128 129 ... 393 394

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