我正在尝试实现Wikipedia中定义的quicksort的简单变体。但是，在我看来，旧的递归调用中的局部变量正在泄漏到以后的调用。 （我目前的解释。）是这样的吗？任何解决方法？
以下是示例代码
# Quick sort - Simple variant. Requires 0(n) extra store
# Divide and conquer. Pick a pivot, compare elements to
# pivot generating two sublists; one greater than pivot
# and the other less than pivot. Sort these two recursively.
# See http://en.wikipedia.org/wiki/Quicksort#Simple_version
function dump_array(arr_arg){
arr_arg_len = length(arr_arg)
RSEP = ORS;
ORS=" ";
dctr = 1;
# Do not use length(arr_arg) in place of arr_arg
# It fails. The following doesn't work
#while (dctr <= arr_arg_len){
while (dctr <= arr_arg_len){
print arr_arg[dctr];
dctr++;
};
ORS = RSEP;
print "\n";
}
function simple_quicksort(unsorted_str)
{
# Unpack from the str - space separated
print "******************************"
print "Called with "unsorted_str
# Split the space separated string into an array
split(unsorted_str, unsorted_array, " ");
array_len = length(unsorted_array);
# No more sorting to be done. Break recursion
if (array_len <= 1){
print "Ending recursion with "unsorted_str
return unsorted_str
}
# Pick a random value as pivot
# index must not be 0
idx = 0
while (idx == 0){
srand()
idx = int(rand() * array_len)
}
pivot = unsorted_array[idx]
if (debug >= 1){
print "idx:"idx" pivot is: "pivot
}
num = 1;
# we don't use the zero'th element,
# this helps us declare an empty array
# dunno any other method
# we'll remove it anyway
less_arr[0] = 0
less_ctr = 1
more_arr[0] = 0
more_ctr = 1
while (num <= array_len){
# Skip pivot
if (idx != num){
if (unsorted_array[num] <= pivot){
if (debug >= 1){
print "Element less than pivot: "unsorted_array[num]
}
less_arr[less_ctr] = unsorted_array[num]
less_ctr++;
}else{
if (debug >= 1){
print "Element more than pivot: "unsorted_array[num]
}
more_arr[more_ctr] = unsorted_array[num]
more_ctr++;
}
}
num++
};
# strip out the holder in idx 0
delete less_arr[0]
delete more_arr[0]
if (debug >= 1){
print "Less than pivot:"
print dump_array(less_arr)
print "More than pivot:"
print dump_array(more_arr)
}
# Marshal array back to a string
less_str=""
less_length = length(less_arr)
num = 1
print "Less length: "less_length
while (num <= less_length){
less_str = less_str" "less_arr[num]
num++;
}
# same thing for more
more_str=""
more_length = length(more_arr)
num = 1
while (num <= more_length){
more_str = more_str" "more_arr[num]
num++;
}
if (debug >= 1){
print "Going for a recursive call with elements < pivot: "less_str
print "Going for a recursive call with elements > pivot: "more_str
print "pivot was: "pivot
}
# Tried to delete the local variables
# Coz it seems like local vars are visible to recursed functions
# Is this why it fails?
delete less_arr
delete more_arr
delete unsorted_array
print "^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"
print ""
return simple_quicksort(less_str) " "pivot" "simple_quicksort(more_str)
}
BEGIN{
print "-- quick sort --"
}
{
# print the unsorted objects
print "Unsorted "NF" objects:\n"$0;
# We'll use a slightly different method,
# Pass the $0 string to the sorter, let it split
# it into an array, qsort that array, generate sub-
# strings and recursively qsort them
#Simple version
sorted = simple_quicksort($0)
}
END{
print "Sorted "NF" objects";
print "Sorted >>"sorted
}
示例运行：
echo 5 12 7 2 13719 28019 21444 30578 30647 | awk -f devel/andorian-blog/awk/sorting/quick_sort.awk -v debug=1
-- quick sort --
Unsorted 9 objects:
5 12 7 2 13719 28019 21444 30578 30647
******************************
Called with 5 12 7 2 13719 28019 21444 30578 30647
idx:1 pivot is: 5
Element more than pivot: 12
Element more than pivot: 7
Element less than pivot: 2
Element more than pivot: 13719
Element more than pivot: 28019
Element more than pivot: 21444
Element more than pivot: 30578
Element more than pivot: 30647
Less than pivot:
2
More than pivot:
12 7 13719 28019 21444 30578 30647
Less length: 1
Going for a recursive call with elements < pivot: 2
Going for a recursive call with elements > pivot: 12 7 13719 28019 21444 30578 30647
pivot was: 5
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with 2
Ending recursion with 2
******************************
Called with 12 7 13719 28019 21444 30578 30647
idx:1 pivot is: 12
Element less than pivot: 7
Element more than pivot: 13719
Element more than pivot: 28019
Element more than pivot: 21444
Element more than pivot: 30578
Element more than pivot: 30647
Less than pivot:
7
More than pivot:
13719 28019 21444 30578 30647
Less length: 1
Going for a recursive call with elements < pivot: 7
Going for a recursive call with elements > pivot: 13719 28019 21444 30578 30647
pivot was: 12
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with 7
Ending recursion with 7
******************************
Called with 13719 28019 21444 30578 30647
idx:3 pivot is: 21444
Element less than pivot: 13719
Element more than pivot: 28019
Element more than pivot: 30578
Element more than pivot: 30647
Less than pivot:
13719
More than pivot:
28019 30578 30647
Less length: 1
Going for a recursive call with elements < pivot: 13719
Going for a recursive call with elements > pivot: 28019 30578 30647
pivot was: 21444
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with 13719
Ending recursion with 13719
******************************
Called with 28019 30578 30647
idx:1 pivot is: 28019
Element more than pivot: 30578
Element more than pivot: 30647
Less than pivot:
More than pivot:
30578 30647
Less length: 0
Going for a recursive call with elements < pivot:
Going for a recursive call with elements > pivot: 30578 30647
pivot was: 28019
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with
Ending recursion with
******************************
Called with 30578 30647
idx:1 pivot is: 30578
Element more than pivot: 30647
Less than pivot:
More than pivot:
30647
Less length: 0
Going for a recursive call with elements < pivot:
Going for a recursive call with elements > pivot: 30647
pivot was: 30578
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with
Ending recursion with
******************************
Called with 30647
Ending recursion with 30647
Sorted 9 objects
Sorted >> 2 5 7 12 13719 21444 28019 30578 30647
那次跑步看起来不错。将它与下一个进行比较：
$ echo 5 12 7 2 13719 28019 21444 30578 30647 | awk -f devel/andorian-blog/awk/sorting/quick_sort.awk -v debug=1
-- quick sort --
Unsorted 9 objects:
5 12 7 2 13719 28019 21444 30578 30647
******************************
Called with 5 12 7 2 13719 28019 21444 30578 30647
idx:6 pivot is: 28019
Element less than pivot: 5
Element less than pivot: 12
Element less than pivot: 7
Element less than pivot: 2
Element less than pivot: 13719
Element less than pivot: 21444
Element more than pivot: 30578
Element more than pivot: 30647
Less than pivot:
5 12 7 2 13719 21444
More than pivot:
30578 30647
Less length: 6
Going for a recursive call with elements < pivot: 5 12 7 2 13719 21444
Going for a recursive call with elements > pivot: 30578 30647
pivot was: 28019
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with 5 12 7 2 13719 21444
idx:4 pivot is: 2
Element more than pivot: 5
Element more than pivot: 12
Element more than pivot: 7
Element more than pivot: 13719
Element more than pivot: 21444
Less than pivot:
More than pivot:
5 12 7 13719 21444
Less length: 0
Going for a recursive call with elements < pivot:
Going for a recursive call with elements > pivot: 5 12 7 13719 21444
pivot was: 2
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with
Ending recursion with
******************************
Called with 5 12 7 13719 21444
idx:3 pivot is: 7
Element less than pivot: 5
Element more than pivot: 12
Element more than pivot: 13719
E lement more than pivot: 21444
Less than pivot:
5
More than pivot:
12 13719 21444
Less length: 1
Going for a recursive call with elements < pivot: 5
Going for a recursive call with elements > pivot: 12 13719 21444
pivot was: 7
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with 5
Ending recursion with 5
******************************
Called with 12 13719 21444
idx:2 pivot is: 13719
Element less than pivot: 12
Element more than pivot: 21444
Less than pivot:
1 2
More than pivot:
21444
Less length: 1
Going for a recursive call with elements < pivot: 12
Going for a recursive call with elements > pivot: 21444
pivot was: 13719
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
******************************
Called with 12
Ending recursion with 12
******************************
Called with 21444
Ending recursion with 21444
******************************
Called with 21444
Ending recursion with 21444
Sorted 9 objects
Sorted >> 2 5 7 12 13719 21444 13719 21444
答案 0 :(得分：8)
在AWK中，您在函数中引用的所有变量都是全局变量。没有“局部变量”这样的东西 但是，AWK中的函数参数的行为类似于局部变量，因为它们在调用嵌套或递归函数时会“隐藏”。 因此，您只需要在函数中获取所有“局部变量”，并将它们作为函数的额外参数添加 调用该函数时，可以省略这些额外的参数。 通常在参数和“局部变量”之间放置一些额外的空间，以便记录您的函数应该如何使用。 此行为和约定记录在GAWK documentation: Function Definition Syntax上。