How can I replace each string match with a different number?

问题

I am trying to replace every with --[[RANDOMNUMBER and textbox1 Text]], but how do I select a new number for each replace, so it's not always 241848 or such?

Random random = new Random();
string replacing = " --[[" + random.Next() + textBox1.Text + "]] ";
string output = richTextBox1.Text.Replace(" ", replacing);

回答1:

Use Regex.Replace(String, String, MatchEvaluator) instead. It takes a MatchEvaluator callback function where you can pull the next random number:

Random random = new Random();
string output = Regex.Replace(richTextBox1.Text, " ", (match) => 
    string.Format(" --[[{0}{1}]] ", random.Next(), textBox1.Text));

For example:

Random random = new Random();
string output = Regex.Replace("this is a test", " ", (match) => 
    string.Format(" --[[{0}{1}]] ", random.Next(), "sample"));

Sample output from above:

this --[[1283057197sample]] is --[[689040621sample]] a --[[1778328590sample]] test

回答2:

Here is a solution using String.Split and Linq Aggregate.

string source = "This is a test string with multiple spaces";
string replaceText = "TextToReplace";
string template = " --[[{0}{1}]] ";
System.Random rand = new System.Random();

var splitString = source.Split(' ');
var result = splitString.Aggregate((a,b) => a + String.Format(template, rand.Next().ToString(), replaceText) + b);

回答3:

Instead of using Replace, you're going to have to use IndexOf and make the replacement yourself, using a new random number every time. Pseudo code:

var index = str.IndexOf(' ');

while (index != -1)
{
    str = str.Substring(0, index) + rand.Next() + str.Substring(index + 1, str.Length - index - 1);
    index = str.IndexOf(' ');
}

I didn't test this so you might wanna check where +1 or -1 is actually in order, and also this can be implemented in a better way. But that's the idea.

回答4:

Your problem is Random is being called only once since Replace takes string parameter. A quick and dirty solution would be

        const string str = "string with lot of spaces";
        var newStr = new StringBuilder();
        foreach (var charc in str.ToCharArray())
        {
            if (charc.Equals(' '))
            {
                var random = new Random();
                var yourReplacementString = " --[[" + random.Next() + "textBox1.Text" + "]] ";
                newStr.Append(yourReplacementString);
            }
            else
            {
                newStr.Append(charc);
            }
        }

回答5:

Consider StringBuilder to avoid many string initialization

var builder = new StringBuilder();

        var stingParts = richTextBox1.Text.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);

        for (int i = 0; i < stingParts.Length; i++)
        {
            builder.Append(stingParts[i]);
            builder.Append(string.Format(" --[[{0}{1}]] ", random.Next(), textBox1.Text)));
        }

        var output = builder.ToString();

来源：https://stackoverflow.com/questions/25851885/how-can-i-replace-each-string-match-with-a-different-number

标签

string

replace