Question

我正在尝试打印用户输入的每个字母的出现列表，但文本框仅显示最后一个字母。

  private void button1_Click(object sender, EventArgs e)
    {
        //disable the text box so text cannot be entered until reset is pressed
        textBox3.Enabled = false;
        //make a list containing the alphabets 
        List<string> Alphabets = new List<string>();
        Alphabets.Add("A");
        Alphabets.Add("B");
        Alphabets.Add("C");
        Alphabets.Add("D");
        Alphabets.Add("E");
        Alphabets.Add("F");
        Alphabets.Add("G");
        Alphabets.Add("H");
        Alphabets.Add("I");
        Alphabets.Add("J");
        Alphabets.Add("K");
        Alphabets.Add("L");
        Alphabets.Add("M");
        Alphabets.Add("N");
        Alphabets.Add("O");
        Alphabets.Add("P");
        Alphabets.Add("Q");
        Alphabets.Add("R");
        Alphabets.Add("S");
        Alphabets.Add("T");
        Alphabets.Add("W");
        Alphabets.Add("X");
        Alphabets.Add("Y");
        Alphabets.Add("Z");

        //make a while loop to cycle through alphabets loop
        int i = 0;
        while (i < Alphabets.Count)
        {                
            //assign value in the list Alphabets
            string SearchFor = Alphabets[i];
            //access textbox and make it to upper small small and captital are the same
            string SearchIn = textBox3.Text.ToUpper();
            //list to count the number of instances used for each letter
            List<int> FoundCount = Search(SearchFor, SearchIn);
            //if statement so only letters that occor more than 0 times are displayed
            if (FoundCount.Count > 0)
            {
                //string to display the number of occorances
                //convert to toString so it can be displayed in the TextBox
                string Counts = Alphabets[i] + ": " + FoundCount.Count.ToString();
                //create a message box to display the output
                //MessageBox.Show(Counts);     
                textBox4.Text =  String.Join(Environment.NewLine, Counts);          
            } 
            //adds 1 each time as long as i <alphabet.count
            i++;
        }
    }
    //List takes 2 arguements (SearchFor, SearchIn) Results can be passed to FoundCounts and number of occrances can be calculted
    List<int> Search(string Target, string Subject)
    {
        //List to count the number of occarances for each letter
        List<int> Results = new List<int>();
        //for loop for comparison (counting occarances) to compare each letter in textbox to each letter in alphabets
        for (int Index = 0; Index < (Subject.Length - Target.Length) + 1; Index++)
        {
            //if to calculate the number of times a letter is used.
            if (Subject.Substring(Index, Target.Length) == Target)
            {
                //adds the number in index to the list Result 
                Results.Add(Index);
            }

        }
        return Results;
    }

我将多线作为真，但是没有效果

Answer 1

我很确定您的代码存在问题：

textBox4.Text = String.Join(Environment.NewLine, Counts);

您每次都会覆盖文本，而应该这样做：

textBox4.Text += String.Join(Environment.NewLine, Counts);

Answer 2

这不是问题的直接答案，但这可能对OP有价值。

此代码执行原始代码所做的所有事情（并修复了问题中提出的问题）：

private void button1_Click(object sender, EventArgs e)
{
    var SearchIn = textBox3.Text.ToUpper();

    var query =
        from c in "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        let count = SearchIn.Count(x => x == c)
        select String.Format("{0}: {1}", c, count);

    textBox4.Text = String.Join(Environment.NewLine, query);        
}

你去了，一个使用列表的版本。： - ）

private void button1_Click(object sender, EventArgs e)
{
    var SearchIn = textBox3.Text.ToUpper();
    var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToList();

    var query =
        from c in alphabet
        let matches = SearchIn.Where((x, n) => x == c).ToList()
        select String.Format("{0}: {1}", c, matches.Count());

    textBox4.Text = String.Join(Environment.NewLine, query);        
}

我试图显示一个字母的出现次数，但输出只显示最后一个字母

2 个答案: