如何检查awk变量的类型? [英] How to check the type of an awk variable?
问题描述
gawk 4.2.0的Beta版本,可在 http:中获得//www.skeeve.com/gawk/gawk-4.1.65.tar.gz 是主要版本,具有许多重要的新功能.
The Beta release of gawk 4.2.0, available in http://www.skeeve.com/gawk/gawk-4.1.65.tar.gz is a major release, with many significant new features.
我之前曾问过 FS的行为是什么?"在GNU Awk 4.2中?,现在我注意到全新的 typeof()
函数弃用了 isarray()
:
I previously asked about What is the behaviour of FS = " " in GNU Awk 4.2?, and now I noticed the brand new typeof()
function to deprecate isarray()
:
从4.1.4更改为4.2.0
Changes from 4.1.4 to 4.2.0
- 新的
typeof()
函数可用于指示变量或数组元素是数组,正则表达式,字符串还是数字.不推荐使用isarray()
函数,而推荐使用typeof()
.
- The new
typeof()
function can be used to indicate if a variable or array element is an array, regexp, string or number. Theisarray()
function is deprecated in favor oftypeof()
.
我可以介绍四种情况:字符串,数字,数组和未分配:
I could cover four cases: string, number, array and unassigned:
$ awk 'BEGIN {print typeof("a")}'
string
$ awk 'BEGIN {print typeof(1)}'
number
$ awk 'BEGIN {print typeof(a[1])}'
unassigned
$ awk 'BEGIN {a[1]=1; print typeof(a)}'
array
但是,我很难获得"regexp"因为我的尝试都没有达到这个目标,并且总是产生数字":
However, I struggle to get "regexp" since none of my attempts reach that and always yield "number":
$ awk 'BEGIN {print typeof(/a/)}'
number
$ awk 'BEGIN {print typeof(/a*/)}'
number
$ awk 'BEGIN {print typeof(/a*d/)}'
number
$ awk 'BEGIN {print typeof(!/a*d/)}'
number
$ awk -v var="/a/" 'BEGIN{print typeof(var)}'
string
$ awk -v var=/a/ 'BEGIN{print typeof(var)}'
string
如何获取定义为"regexp"的变量?
How can I get a variable to be defined as "regexp"?
我注意到上一个项目符号:
I noticed the previous bullet:
- Gawk现在支持强类型的正则表达式常量.这样的常量看起来像@/.../.您可以将它们分配给变量,将它们传递给函数,在〜,!〜和switch语句的case部分中使用它们.手册中提供了更多详细信息.
尝试了一下,但是没有运气:
And tried a bit, but with no luck:
$ awk -v pat=@/a/ '{print typeof(pat)}' <<< "bla ble"
string
推荐答案
typeof(/a/)
在 $ 0的结果上运行
是一个数字.我本人还没有尝试过,但是我希望这是您正在寻找的东西: typeof()
〜/a/
typeof(/a/)
is running typeof()
on the result of $0 ~ /a/
which is a number. I haven't tried this yet myself but I'd expect this to be what you're looking for:
typeof(@/a/)
和
var = @/a/
typeof(var)
这可行:
So this works:
$ awk 'BEGIN {print typeof(@/a/)}'
regexp
$ awk 'BEGIN {var=@/a/; print typeof(var)}'
regexp
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