awk匹配字段有奇怪现象，请高手指点

ly5066113

回复 29# reyleon


因此
想要得到 STRNUM 型的变量，我们可以用 -v 的方式赋值
想要得到 STRING 型的变量，我们可以在 awk内部 赋值

两者恰恰是一个很好的互补。

liuyu85

怎么还讨论的这么热烈？我在11楼说的很清楚啦。。。。。
与BEGIN本身无关，与shell解析还是awk解析有关。
-v的部分是shell解析，awk单引号内部是awk解析。awk解析遇到双引号的都认为是字符串。。。。
还有异议嘛？

聆雨淋夜

回复 24# ly5066113
ly大师：我可不可以这样理解，反正$1不可能为string，以后做比较的时候，我只需要判断id是数字还是字符串，就能确定按数字还是字符串比较了。


   

ly5066113

回复 33# 聆雨淋夜


前提是 $1 里的内容为纯数字。

聆雨淋夜

回复 34# ly5066113
http://blog.chinaunix.net/uid-10540984-id-4371071.html
这是zooyo的一篇博客，他在里面举了一个例子。
他说awk把纯数字3当做字符串处理了，他是说错了么

   

reyleon

回复 35# 聆雨淋夜


zooyo说的没错呀,  awk 中数组的下标(index), 它总是 STRING 类型, 遇到字符串与数字做比较时,以 STRING 做比较操作.

聆雨淋夜

回复 36# reyleon
我是看了你贴出来的段落，以为数组元素是strnum  
Fields, getline input, FILENAME, ARGV elements, ENVIRON elements, and the elements of an array created by match(), split(), and patsplit() that are numeric strings have the strnum attribute.Otherwise, they have the string attribute. Uninitialized variables also have the strnum attribute.

   

聆雨淋夜

回复 36# reyleon
六哥对不起，我把参数元素看成数组元素了。

   

reyleon

回复 35# 聆雨淋夜


跟 awk 的版本有关系, awk 4.0+ 的版本不会有这个问题. awk 3.x 版本中或许没有引入 STRNUM 类型.

[root@localhost ~]# echo -e '20.7\n25.5\n3'| /bin/awk '{a[$0]}END{for(i in a){if(i>20)print i}}'
20.7
25.5
3
[root@localhost ~]# /bin/awk --version
GNU Awk 3.1.5
Copyright (C) 1989, 1991-2005 Free Software Foundation.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
[root@localhost ~]#
[root@localhost ~]# echo -e '20.7\n25.5\n3'| awk '{a[$0]}END{for(i in a){if(i>20)print i}}'     
25.5
20.7
[root@localhost ~]# awk --version
GNU Awk 4.1.1, API: 1.1
Copyright (C) 1989, 1991-2014 Free Software Foundation.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/.
[root@localhost ~]#

reyleon

又翻到此贴, 突然发现, 居然是跟什么什么鬼浮点数精度有关, 在gawk 4.1+版本中, 加上-M参数, 数值比较也是没问题的

$ cat file
0001000002013022008310010420130220083100201302200831000000000001
201506021717179991015   10元包月        0       Free    1       Fee=600 20130220083430  20130220083430
201506021717179991025   10元包月        0       Free    1       Fee=700 20130220083430  20130220083430
201506021717179991035   10元包月        0       Free    1       Fee=800 20130220083430  20130220083430
201506021717179991045   10元包月        0       Free    1       Fee=900 20130220083430  20130220083430

reyleon@DESKTOP-T440P ~
$ awk --version
GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0)
Copyright (C) 1989, 1991-2015 Free Software Foundation.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/.

reyleon@DESKTOP-T440P ~
$ awk -M -v id='201506021717179991015' '{if($1==id){print $0;next}}' file
201506021717179991015   10元包月        0       Free    1       Fee=600 20130220083430  20130220083430