Referencing Macro Variables Indirectly问题

1549

收藏 2014-11-13

关于 [size=16.000000pt]Referencing Macro Variables Indirectly这块是死活弄不明白了。
[size=16.000000pt]例子如下：运行以下程序，不同个数的&，是怎么re-scan神马的得到下面结果的啊？？？真心是醉了！请问哪位大仙抽空给指点一下！！！
程序：
%let test=one;
%let one=two;
%let two=three;
%let three=four;
%let four=five;
%put 5:&&&&&test;
%put 6:&&&&&&test;
%put 7:&&&&&&&test;
%put 8:&&&&&&&&test;
%put 9:&&&&&&&&&test;
%put 10:&&&&&&&&&&test;

结果：

1       OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
42       ;
43       %let test=one;
44       %let one=two;
45       %let two=three;
46       %let three=four;
47       %let four=five;
48       %put 5:&&&&&test;
5:two
49       %put 6:&&&&&&test;
6:two
50       %put 7:&&&&&&&test;
7:three
51       %put 8:&&&&&&&&test;
8:one
52       %put 9:&&&&&&&&&test;
9:two
53       %put 10:&&&&&&&&&&test;
10:two
54
55       ;
56       OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
66       ;

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全部回复

liulubucm

2014-11-13 06:40:33

补充一下，用symbolgen option也晕晕乎乎不太懂
1       OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
SYMBOLGEN:  Macro variable _SASWSTEMP_ resolves to /folders/myfolders/.images/ab872ba3-2cff-4295-aa65-1f2c0ebb757c
SYMBOLGEN:  Some characters in the above value which were subject to macro quoting have been unquoted for printing.
SYMBOLGEN:  Macro variable _SASWSTEMP_ resolves to /folders/myfolders/.images/ab872ba3-2cff-4295-aa65-1f2c0ebb757c
SYMBOLGEN:  Some characters in the above value which were subject to macro quoting have been unquoted for printing.
SYMBOLGEN:  Macro variable GRAPHINIT resolves to
42       ;
43       %let test=one;
44       %let one=two;
45       %let two=three;
46       %let three=four;
47       %let four=five;
48       %put 5:&&&&&test;
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable TEST resolves to one
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable ONE resolves to two
5:two
49       %put 6:&&&&&&test;
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable TEST resolves to one
SYMBOLGEN:  Macro variable ONE resolves to two
6:two
50       %put 7:&&&&&&&test;
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable TEST resolves to one
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable ONE resolves to two
SYMBOLGEN:  Macro variable TWO resolves to three
7:three
51       %put 8:&&&&&&&&test;
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable TEST resolves to one
8:one
52       %put 9:&&&&&&&&&test;
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable TEST resolves to one
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable ONE resolves to two
9:two
53       %put 10:&&&&&&&&&&test;
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable TEST resolves to one
SYMBOLGEN:  && resolves to &.
SYMBOLGEN:  Macro variable ONE resolves to two
10:two
54
55       ;
56       OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
SYMBOLGEN:  Macro variable GRAPHTERM resolves to
66       ;

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pobel

2014-11-13 09:06:48

SAS宏处理器在解析带有&的字符串时，大致的规则是这样的：
1. 顺序是从左到右；
2. 两个连续的&&，处理成单个&;
3. &后跟宏变量名字，那就解析出宏变量的值；
4. 回到第1步，直到解析结束。

例如：%put 7:&&&&&&&test;解析过程是：
7:&&&one
7:&two
7:three

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liulubucm

2014-11-14 00:45:52

pobel 发表于 2014-11-13 09:06
SAS宏处理器在解析带有&的字符串时，大致的规则是这样的：
1. 顺序是从左到右；
2. 两个连续的&&，处理成 ...

哦，如果是这样，是不是可以理解为：
%put 8:&&&&&&&&test;解析过程是：
8：&&&&test
8：&&test
8：&test
8：one
%put 9:&&&&&&&&&test;解析过程是：
9：&&&&one；
9：&&one；
9：&one；
9：two；
%put 10:&&&&&&&&&&test;解析过程是：
10：&&&&&test；
10：&&one；
10：&one；
10：two；
%put 11：&&&&&&&&&&&test；
11：&&&&&one；
11：&&two;
11: &two;
11: three;
好像确实是对的啊！
茅塞顿开！

非常感谢！

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lqyrendajinji

2014-11-14 01:02:04

xuexi xuexi

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