Question

是否存在与VB6中的TextFieldParser类等效的现代.NET？性能远低于简单的String.Split()

Answer 1

我已将效果与该代码进行了比较：https://gist.github.com/Ruszrok/7861319

我使用了一个输入文件，其中大约有1 000 000条记录用空格分隔。我尝试了五次实验。

String.Split平均时间： 291 ms
Microsoft.VisualBasic.FileIO.TextFieldParser平均时间： 15843 ms

您可以使用Microsoft.VisualBasic.FileIO.TextFieldParser课程。参考Microsoft.VisualBasic。主旨中的样本。

Answer 2

这是我的解决方案：

public class TextFieldParser
    {
        enum FieldType { FixedWidth, Delimited };

        public enum CompleteElements 
        {
            /// <summary>
            /// Returns as many elements as fileWidths input be
            /// </summary>
            AllElements, 
            /// <summary>
            /// Only returns elements who have not null values
            /// </summary>
            OnlyValues 
        };

        int[] m_fieldWidths;
        string m_line;
        List<string> m_results;
        int m_lineWidth;
        public CompleteElements m_CompleteElements;

        public TextFieldParser(string line)
        {
            m_line = line;
            m_lineWidth = m_line.Length;
            m_results = new List<string>();
            m_CompleteElements = CompleteElements.OnlyValues;
        }

        public void SetCompleteElements(CompleteElements value) 
        {
            m_CompleteElements = value;
        }

        public void SetFieldWidths(params int[] fileWidths)
        {
            m_fieldWidths = fileWidths;
        }

        public string[] ReadFields()
        {
            int pivot = 0;
            m_results = new List<string>();

            for (int x = 0; x < m_fieldWidths.Length; x++) 
            {
                if(pivot + m_fieldWidths[x] <= m_lineWidth)
                {
                    m_results.Add(m_line.Substring(pivot, m_fieldWidths[x]));                    
                }
                else
                {
                    if (m_CompleteElements == CompleteElements.AllElements) 
                    {
                        m_results.Add(null);
                    }

                    break;
                }
                pivot += m_fieldWidths[x];
            }
            return m_results.ToArray();
        }
    }

一个简单的会话：

string line = "1234567890123456789012345678890";
TextFieldParser parser = new TextFieldParser(line);
parser.SetFieldWidths(1, 2, 3, 4, 5, 6, 7, 8);

string[] resultOnlyValues = parser.ReadFields();
/*
results:
resultOnlyValues[0] : "1"
resultOnlyValues[1] : "23"
resultOnlyValues[2] : "456"
resultOnlyValues[3] : "7890"
resultOnlyValues[4] : "12345"
resultOnlyValues[5] : "678901"
resultOnlyValues[6] : "2345678"
*/
parser.SetCompleteElements(TextFieldParser.CompleteElements.AllElements);
string[] resultAllElement = parser.ReadFields();
/*
results:
resultAllElement[0] : "1"
resultAllElement[1] : "23"
resultAllElement[2] : "456"
resultAllElement[3] : "7890"
resultAllElement[4] : "12345"
resultAllElement[5] : "678901"
resultAllElement[6] : "2345678"
resultAllElement[7] : null
*/

TextFieldParser等效于.NET？

2 个答案: