从文本框中的给定字符串中提取子字符串 [英] Extracting a substring from a given string in textbox

问题描述

您好，

我想从用户在C＃中输入文本框的字符串中提取子字符串。我需要的子串将在输入的字符串之间。

例如，如果用户输入select asd，fkdl from table，

，

我需要asd，fkdl作为我的子串。



我该怎么做请帮助。



我尝试了什么：

Hello,
I want to extract a substring from a string which the user enters into the textbox in C#. The substring I need would be in between the string entered.
For example,
if the user enters "select asd,fkdl from table",
I need "asd,fkdl" as my substring.

How do I do that Please help.

What I have tried:

private void textBox1_TextChanged(object sender, EventArgs e)
        {
            string x = (sender as Control).Text;
            string temp;
            listBox1.BeginUpdate();
            string str = textBox1.Text.ToString();
            int p = str.IndexOf(' ');
            int len = str.Length;
            try
            {
                for (int i = 8; str[i] != ' '; i++)
                {
                    var substr = str.Substring(8,i+1);
                    temp = substr;
                    MessageBox.Show(temp,"Substring");
                }  
}
            finally
            {
                listBox1.EndUpdate();
            }

推荐答案

现在是时候了解正则表达式 [ ^ ]。

It is time to learn about Regular Expressions[^].

使用正则表达式：

Use a regex:

string input = "select asd,fkdl from table";
Match m = Regex.Match(input, @"(?<=select\s+).+?(?=\s+from)", RegexOptions.IgnoreCase);
if (m.Success)
    {
    string substr = m.Value;
    }

，不使用正则表达式

without using Regex

string input = "select asd,fkdl from table";
        int start = input.IndexOf("select")+6;
        var columns =  input.Substring(start, input.IndexOf("from") - start).Trim(); //"asd,fkdl"

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