How to solve the performance problem of string concatenation in VBS
This article will explain in detail how to solve the performance problem of string connection in VBS. Xiaobian thinks it is quite practical, so share it with you as a reference. I hope you can gain something after reading this article.
Of course, efficiency doesn't really matter much to the program for a small number of string concatenations, so let's consider an extreme problem: concatenating all numbers between 1 and 100000 into a string.
The simplest solution is to use & Connect directly:
The copy code is as follows:
begin = Timer
For i = 1 To 100000
str = str & CStr(i)
Next
WScript.Echo str
finish = Timer
WScript.Echo finish - begin
But this program takes 60.648 seconds to run on my computer, which is too inefficient. In other words, use the array to solve:
The copy code is as follows:
begin = Timer
Dim arr(100000)
For i = 1 To 100000
arr(i) = i
Next
str = Join(arr, "")
WScript.Echo str
finish = Timer
WScript.Echo finish - begin
This time it took only 0.742 seconds, which is about 60 times faster. In this case, the size of the array can be determined in advance, and dynamic arrays must be used if the size of the array cannot be predicted. I am relatively low level, will not use dynamic array, there is no simpler way? The answer is yes, and that is the dictionary:
The copy code is as follows:
begin = Timer
Set oDic = CreateObject("scripting.dictionary")
For i = 1 To 100000
oDic.Add i, CStr(i)
Next
str = Join(oDic.Items, "")
WScript.Echo str
finish = Timer
WScript.Echo finish - begin
The runtime is 1.593, twice as long as arrays, but still much faster than & and easier to use than arrays.
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