How to replace “http:” with “https:” in a string with C#?

Question

I've stored all URLs in my application with "http://" - I now need to go through and replace all of them with "https:". Right now I have:

    foreach (var link in links)
        {
            if (link.Contains("http:"))
            {
                /// do something, slice or replace or what?
            }
        }

I'm just not sure what the best way to update the string would be. How can this be done?

Answer 1

If you're dealing with uris, you probably want to use UriBuilder since doing a string replace on structured data like URIs is not a good idea.

var builder = new UriBuilder(link);
builder.Scheme = "https";
Uri modified = builder.Uri;

It's not clear what the type of links is, but you can create a new collection with the modified uris using linq:

IEnumerable<string> updated = links.Select(link => {
    var builder = new UriBuilder(link);
    builder.Scheme = "https";
    return builder.ToString();
});

Answer 2

The problem is your strings are in a collection, and since strings are immutable you can't change them directly. Since you didn't specify the type of links ( List ? Array ?) the right answer will change slightly. The easiest way is to create a new list:

links = links.Select(link => link.Replace("http://","https://")).ToList();

However if you want to minimize the number of changes and can access the string by index you can just loop through the collection:

for(int i = 0; i < links.Length; i++ )
{
    links[i] = links[i].Replace("http://","https://");
}

Answer 3

based on your current code, link will not be replace to anything you want because it is read only (see here: Why can't I modify the loop variable in a foreach? ). instead use for

for(int a = 0; a < links.Length; a++ )
{
    links[a] = links[a].Replace("http:/","https:/")
}

Answer 4

使用string.Replace和一些LINQ：

var httpsLinks = links.Select(l=>l.Replace("http://", "https://");

Answer 5

http://myserver.xom/login.aspx?returnurl= http %3a%2f%2fmyserver.xom%2fmyaccount.aspx&q1=a%20b%20c&q2=c%2b%2b

What about the urls having also url in the querystring part? I think we should also replace them. And because of the url encoding-escaping this is the hard part of the job.

private void BlaBla()
{
    // call the replacing function
    Uri myNewUrl = ConvertHttpToHttps(myOriginalUrl);
}

private Uri ConvertHttpToHttps(Uri originalUri)
{
    Uri result = null;
    int httpsPort = 443;// if needed assign your own value or implement it as parametric 

    string resultQuery = string.Empty;
    NameValueCollection urlParameters = HttpUtility.ParseQueryString(originalUri.Query);

    if (urlParameters != null && urlParameters.Count > 0)
    {
        StringBuilder sb = new StringBuilder();
        foreach (string key in urlParameters)
        {
            if (sb.Length > 0)
                sb.Append("&");

            string value = urlParameters[key].Replace("http://", "https://");
            string valuEscaped = Uri.EscapeDataString(value);// this is important
            sb.Append(string.Concat(key, "=", valuEscaped));
        }
        resultQuery = sb.ToString();
    }

    UriBuilder resultBuilder = new UriBuilder("https", originalUri.Host, httpsPort, originalUri.AbsolutePath);
    resultBuilder.Query = resultQuery;

    result = resultBuilder.Uri;
    return result;
}