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= (equality)
Equal--binary (Relational)
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Syntax
<exp1> = <exp2>
Type
Character, date, logical, memo, NIL, numeric
Operands
<exp1> and <exp2> are expressions of the same data type to
compare.
Description
The equal operator (= ) compares two values of the same data type and
returns true (.T.) if <exp1> is equal to <exp2> according to the
following rules:
. Character: The comparison is based on the underlying ASCII
code. ASCII codes for alphabetic characters are ascending (e.g., the
code for "A" is 65 and the code for "Z" is 90).
When EXACT is OFF, two character strings are compared according to
the following rules. assume two character strings, cLeft and cRight,
where the expression to test is (cLeft = cRight):
- If cRight is null, returns true (.T.).
- If LEN(cRight) is greater than LEN(cLeft), returns false
(.F.).
- Compare all characters in cRight with cLeft. If all
characters in cRight equal cLeft, returns true (.T.); otherwise,
returns false (.F.).
With EXACT ON, two strings must match exactly except for trailing
blanks.
. Date: Dates are compared according to the underlying date
value.
. Logical: True (.T.) is equal to true (.T.) and false (.F.)
equal to false (.F.).
. Memo: Treated the same as character.
. NIL: True (.T.) if compared to a NIL value; false (.F.) if
compared to a value of any other data type.
. Numeric: Compared based on magnitude.
Examples
. These examples illustrate how the equal operator (=) behaves
with different data types:
// Character
SET EXACT ON
? "123" = "123 " // Result: .T.
? " 123" = "123" // Result: .F.
SET EXACT OFF
? "123" = "12345" // Result: .F.
? "12345" = "123" // Result: .T.
? "123" = "" // Result: .T.
? "" = "123" // Result: .F.
// Date
? CTOD("12/12/88") = ;
CTOD("12/12/88") // Result: .T.
// Logical
? .T. = .T. // Result: .T.
? .F. = .T. // Result: .F.
// NIL
? NIL = NIL // Result: .T.
? NIL = 12 // Result: .F.
? NIL = CTOD("") // Result: .F.
// Numeric
? 2 = 1 // Result: .F.
? 1 = 1 // Result: .T.
See Also:
$
<
<=
<>
==
>
>=
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Written by Dave Pearson