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71 lines
2.3 KiB
Plaintext
71 lines
2.3 KiB
Plaintext
The [[LEFT$]] string function returns a number of characters from the left of a [[STRING]].
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{{PageSyntax}}
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: [[LEFT$]]({{Parameter|stringValue$}}, {{Parameter|numberOfCharacters%}})
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{{Parameters}}
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* {{Parameter|stringValue$}} can be any [[STRING]] literal or variable.
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* {{Parameter|numberOfCharacters%}} [[INTEGER]] determines the number of characters to return from left of string.
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{{PageDescription}}
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* If the number of characters exceeds the string length the entire string is returned. Use [[LEN]] to determine a string's length.
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* [[LEFT$]] returns always start at the first character of the string, even if it's a space. [[LTRIM$]] can remove leading spaces.
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* '''{{Parameter|numberOfCharacters%}} cannot be a negative value.'''
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{{PageExamples}}
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''Example 1:'' Getting the left portion of a string value.
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{{CodeStart}} '' ''
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name$ = "Tom Williams"
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First$ = LEFT$(name$, 3)
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PRINT First$ '' ''
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{{CodeEnd}}
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{{OutputStart}}Tom {{OutputEnd}}
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''Example 2:'' A replace function using LEFT$ and [[RIGHT$]] with [[INSTR]] to insert a different length word into an existing string.
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{{CodeStart}} '' ''
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text$ = "This is my sentence to change my words."
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{{Cl|PRINT}} text$
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oldword$ = "my"
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newword$ = "your"
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x = Replace(text$, oldword$, newword$)
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{{Cl|IF...THEN|IF}} x {{Cl|THEN}} {{Cl|PRINT}} text$; x
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{{Cl|END}}
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{{Cl|FUNCTION}} Replace (text$, old$, new$) 'can also be used as a {{Cl|SUB}} without the count assignment
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{{Cl|DO...LOOP|DO}}
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find = {{Cl|INSTR}}(start + 1, text$, old$) 'find location of a word in text
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{{Cl|IF...THEN|IF}} find {{Cl|THEN}}
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count = count + 1
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first$ = {{Cl|LEFT$}}(text$, find - 1) 'text before word including spaces
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last$ = {{Cl|RIGHT$}}(text$, {{Cl|LEN}}(text$) - (find + {{Cl|LEN}}(old$) - 1)) 'text after word
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text$ = first$ + new$ + last$
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{{Cl|END IF}}
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start = find
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{{Cl|LOOP}} {{Cl|WHILE}} find
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Replace = count 'function returns the number of replaced words. Comment out in SUB
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{{Cl|END FUNCTION}} '' ''
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{{CodeEnd}}
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{{OutputStart}}This is my sentence to change my words.
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This is your sentence to change your words.{{OutputEnd}}
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: ''Note:'' The [[MID$ (statement)|MID$]] statement can only substitute words or sections of the original string length. It cannot change the string length.
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{{PageSeeAlso}}
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* [[RIGHT$]], [[MID$]]
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* [[LTRIM$]], [[RTRIM$]]
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* [[MID$ (statement)]]
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* [[INSTR]], [[LEN]]
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{{PageNavigation}}
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