Article: Q133740
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s):
Keyword(s):
Last Modified: 15-FEB-2000
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The information in this article applies to:
- Microsoft Visual FoxPro for Windows, version 3.0
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SUMMARY
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The null value (.NULL.) is not an actual value, it is a marker that denotes that
a memory variable or a field value is missing or unknown. If .NULL. is assigned
to a field or a variable, the field or variable's data type is not changed, but
the value is changed to NULL.
MORE INFORMATION
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Steps to Demonstration Behavior
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The .NULL. value can be assigned to variables that are numeric or character as
demonstrated by these steps:
1. From the Command window, issue these commands:
nMyvariable=200 && and press ENTER
? TYPE("nMyvariable") && and press ENTER
? nMyvariable
The N is displayed for nMyvariable denoting a variable of numeric type.
2. To assign a null value (.NULL.) to nMyvariable, issue the following commands
in the Command window:
store .NULL. to nMyvariable && and press ENTER
? TYPE("nMyvariable") && and press ENTER
? nMyvariable && and press ENTER
The value N is displayed followed by .NULL.; the type of the variable did not
change but the value did.
3. To assign a character string to the variable and check the variable type,
issue the following commands in the Command window:
cMyvariable="This is a String" && and press ENTER
? cMyvariable && and press ENTER
The screen displays the string "This is a String."
4. Issue the following command in the Command window:
? TYPE("cMyvariable") && and press ENTER
The screen displays C denoting a character type.
5. Issue the following commands in the Command window:
STORE .NULL. TO cMyvariable && and press ENTER
?TYPE("cMyvariable") && and press ENTER
The screen displays C to show that the type has not been changed.
Additional query words: VFoxWin
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Keywords :
Technology : kbVFPsearch kbAudDeveloper kbVFP300
Version : WINDOWS:3.0
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