code does not insert all elements of array to string

Question

i have this code which should insert all elements of array which is some html on random places in a string. but it only inserts last element to that string. please help

Random insertPos = new Random();
int pos = insertPos.Next(txtInput.Text.Length);
int firSpace= txtInput.Text.IndexOf(" ", pos);
int secSpace = txtInput.Text.IndexOf(" ", firSpace+1);
int wLen = secSpace - firSpace;<br/>
string word = txtInput.Text.Substring(firSpace,wLen);
foreach (string url in urlArray)
{
    txtOutput.Text = 
         txtInput.Text.Replace(word, "<a href=\"" + url + "\">" + word + "</a>");
}

jason · Accepted Answer · 2010-12-13 14:57:18Z

2

You are replacing (=) the contents of txtOutput.Text on every iteration so of course you are only going to see the last result. Consider using +=¹ first to get it working and then a StringBuilder if your performance is suffering and this is a bottleneck.

¹: It's not clear exactly how you want it formatted, but at least += will append and assign the result of the append instead of just the result of the current iteration.

answered Dec 13, 2010 at 14:57

jason

243k36 gold badges437 silver badges532 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

toad Over a year ago

my problem is, i have a string, say 200 words long, have an array which contains urls, say 4 urls. i want to embed those urls in string at random places, if i use <code>+=</code> it creates as many copies of original string as i have urls in array and embeds html around same word in all copies.

MatthiasG · Accepted Answer · 2010-12-13 14:58:05Z

1

You overwrite the Text property of the textbox in every step of the foreach loop. Only the result of last loop will be left.

answered Dec 13, 2010 at 14:58

MatthiasG

4,5603 gold badges30 silver badges48 bronze badges

Comments

Karl Knechtel · Accepted Answer · 2010-12-13 15:00:50Z

1

You are repeatedly saying "figure out what happens when I insert the HTML into txtInput 's text, and assign the result to the txtOutput text". But this does not actually change the text in txtInput, so you are starting fresh each time; and you throw away the txtOutput text each time to replace it with the new stuff.

answered Dec 13, 2010 at 15:00

Karl Knechtel

61.4k14 gold badges134 silver badges193 bronze badges

Comments

Branimir · Accepted Answer · 2010-12-13 15:28:52Z

As Jaison said you are using = instead of +=, but there are better solutions. Remember that strings are immutable. Use string.Format or StringBuilder where you're concatenating strings. Examples:

string[] strArray = {"a", "b", "c"};
string word = "word";

//1st solution +=
string output = "";

foreach (string str in strArray)
    output += "<a href=\"" + str + "\">" + word + "</a>";

Console.WriteLine(output);

//better solution string.Format
output = "";

foreach (string str in strArray)            
    output += string.Format("<a href=\"{0}\">{1}</a>", str, word);

Console.WriteLine(output);

//StringBuilder
StringBuilder sb = new StringBuilder();

foreach (string str in strArray)            
    sb.AppendFormat("<a href=\"{0}\">{1}</a>", str, word);

output = sb.ToString();

Console.WriteLine(output);

//linq & string.Join
output = string.Join("", strArray.Select( str => string.Format("<a href=\"{0}\">{1}</a>", str, word)).ToArray());

Console.WriteLine(output);

Console.Read();

Collectives™ on Stack Overflow

code does not insert all elements of array to string

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related