the global and the local macro symblo table

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The global symbol table is
created during the initialization of a SAS session or noninteractive execution
initialized with automatic or system-defined macro variables
deleted at the end of the session.
Macro variables in the global symbol table
are available anytime during the session
can be created by your program
have values that can be changed during the session (except some automatic macro variables)
cannot be removed once they are created (they can be assigned a null value).
A local symbol table is
created when a macro with a parameter list is called or a request is made to create a local variable during macro execution
deleted when the macro finishes execution.
The local symbol table contains macro variables that can be
created and initialized at macro invocation (parameters)
created during macro execution
updated during macro execution
referenced anywhere within the macro.

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关键词：Global lobal Macro Table Local available assigned created except cannot

crackman 发表于 2010-4-7 08:44
The global symbol table is
created during the initialization of a SAS session or noninteractive execution
initialized with automatic or system-defined macro variables
deleted at the end of the session.
Macro variables in the global symbol table
are available anytime during the session
can be created by your program
have values that can be changed during the session (except some automatic macro variables)
cannot be removed once they are created (they can be assigned a null value).
A local symbol table is
created when a macro with a parameter list is called or a request is made to create a local variable during macro execution
deleted when the macro finishes execution.
The local symbol table contains macro variables that can be
created and initialized at macro invocation (parameters)
created during macro execution
updated during macro execution
referenced anywhere within the macro.

" .... cannot be removed once they are created (they can be assigned a null value)."

This is absolete. After SAS introduces the "%SYMDEL". See below.


1    %let gmvar=glabol_var;
2
3    %put >>>&gmvar<<<;
>>>glabol_var<<<
4
5    %SYMDEL gmvar;
6
7    %put >>>&gmvar<<<;
WARNING: Apparent symbolic reference GMVAR not resolved.
>>>&gmvar<<<

2# bobguy
bobguy
thank you
i  find this function in macro in help manual
i wanna to learn from u