有什么办法可以让此C＃代码更快？ [英] Is there any way I can make this C# code faster?

问题描述

我读一个大文件X12和解析内的信息。我有两个瓶颈的功能，我似乎无法变通。 read_line（）和get_element（）有什么办法，我可以让这两个函数更快？在get_element功能的主要瓶颈似乎是子串的方法。

 公共字符串get_element（INT将Element_number）{
诠释计数= 0; 
 INT START_INDEX = 0; 
 INT END_INDEX = 0; 
 INT CURRENT_INDEX = 0; 
 
，而（COUNT<将Element_number&放大器;&安培;！CURRENT_INDEX = -1）{
 = CURRENT_INDEX line_text.IndexOf（x12_reader.element_delimiter，START_INDEX）; 
 START_INDEX = CURRENT_INDEX + 1; 
计数++; 
} 
 
如果（CURRENT_INDEX！= -1）{
 END_INDEX = line_text.IndexOf（x12_reader.element_delimiter，START_INDEX）; 
如果（END_INDEX == -1）= END_INDEX line_text.Length; 
返回line_text.Substring（START_INDEX，END_INDEX  -  START_INDEX）; 
}其他{
返回; 
} 
} 
 
私人字符串read_line（）{
 string_builder.Clear（）; 
 INT N; 
，而（（N = stream_reader.Read（））！= -1）{
如果（N == line_terminator）返回string_builder.ToString（）; 
 string_builder.Append（（char）的N）; 
} 
返回string_builder.ToString（）; 
} 
  

我读X12的数据。这里是什么样子的例子。 http://examples.x12.org/005010X221/dollars-and-数据发送在一起/

解决方案

由于您的分析器告诉你 get_element 是一个瓶颈，方法本身是非常有效的编码，你需要减少的时候调用此方法的次数。

调用 get_element 反复循环的力量是重复执行相同的分析工作：

 为（ INT I = 0; i = N;！我++）{$​​ b $ b VAR元= get_element（I） 
 ... //做的元素
} 
的东西 

您应该可以通过重写来解决这个问题 get_element 为的getElements 返回所有元素的集合，然后采取从各个元素同一集合在一个循环：

  VAR allElements =的getElements（）; 
的for（int i = 0; i = N;！我++）{$​​ B $ B VAR元= allElements [I] 
 ... //做的元素
} 
  

$ B的东西$ b

在大多数情况下，我只需要一个或两个元素

在这种情况下，你可以使检索所有必需的方法同时指标 - 例如，通过传递的 BitArray 所需的索引。

I am reading in a large file X12 and parsing the information within. I have two bottleneck functions that I can't seem to work around. read_line() and get_element() Is there any way I could make these two functions faster? The main bottleneck in the get_element function seems to be the Substring method.

    public String get_element(int element_number) {
        int count = 0;
        int start_index = 0;
        int end_index = 0;
        int current_index = 0;

        while (count < element_number && current_index != -1) {
            current_index = line_text.IndexOf(x12_reader.element_delimiter, start_index);
            start_index = current_index + 1;
            count++;
        }

        if (current_index != -1) {
            end_index = line_text.IndexOf(x12_reader.element_delimiter, start_index);
            if (end_index == -1) end_index = line_text.Length;
            return line_text.Substring(start_index, end_index - start_index);
        } else {
            return "";
        }
    }

    private String read_line() {
        string_builder.Clear();
        int n;
        while ((n = stream_reader.Read()) != -1) {
            if (n == line_terminator) return string_builder.ToString();
            string_builder.Append((char)n);
        }
        return string_builder.ToString();
    }

I am reading x12 data. Here is an example of what it looks like. http://examples.x12.org/005010X221/dollars-and-data-sent-together/

解决方案

Since your profiler tells you get_element is a bottleneck, and the method itself is coded very efficiently, you need to minimize the number of times this method is called.

Calling get_element repeatedly in a loop forces it to performs the same parsing job repeatedly:

for (int i = 0 ; i != n ; i++) {
    var element = get_element(i);
    ... // Do something with the element
}

You should be able to fix this problem by rewriting get_element as GetElements returning all elements as a collection, and then taking individual elements from the same collection in a loop:

var allElements = GetElements();
for (int i = 0 ; i != n ; i++) {
    var element = allElements[i];
    ... // Do something with the element
}

in most cases I only need one or two elements

In this case you could make a method that retrieves all required indexes at once - for example, by passing BitArray of required indexes.

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