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Custom string from TextBox in webrequest

i am trying to send a HttpWebRequest with the following body :
string body = "{\"prompt\": \"MyText\",\"n\": 2,\"size\": \"256x256\",\"response_format\":\"b64_json\"}";
the request works perfectly with this body, but everytime i try to change "MyText" with a text from textbox, i get an error 400 from server.
i tried this (return error 400):
string body = "{\"prompt\":" +textBox1.Text+",\"n\": 2,\"size\": \"256x256\",\"response_format\":\"b64_json\"}";
any ideas ?

It is not recommended to build your JSON manually as you will highly expose to syntax errors due to missing/extra quotes, braces, etc especially when dealing with complex objects/arrays.
Using the libraries such as System.Text.Json or Newtonsoft.Json for the JSON serialization. This is safer and easier compared to building it manually.
using System.Text.Json;
var obj = new
{
prompt = textBox1.Text,
n = 2,
size = "256x256",
response_format = "b64_json"
};
string body = JsonSerializer.Serialize(obj);
using Newtonsoft.Json;
string body = JsonConvert.SerializeObject(obj);

Need to extract a specific url from source code in c# console

Im making a bot that needs to display images from page links that are user fed. The only way i see of doing this is getting the href code from the source code
using (WebClient client = new WebClient())
{
string htmlCode = client.DownloadString("url that is input by the user");
Console.WriteLine(htmlCode);
Console.ReadKey();
}
is the current code that gets a url. If it helps, this query targets the card pages on the duelmaster wiki so the page layout is identical. I guess what im trying to ask is how do i get that code from the entire source code file?

You can use regex to extract href data from a string
Regular Expression :-
href[\s]=[\s]\"(.?)[\s]\"
C# Code
Include namespace
using System.Text.RegularExpressions;
Updated Code
static void Main()
{
Console.WriteLine("Enter Url you want to Extract data from");
string userInput = Console.ReadLine();
Task t = new Task(DownloadPageAsync);
t.Start();
Console.WriteLine("Downloading page...");
Console.ReadLine();
}
static async void DownloadPageAsync(string requestUrl)
{
// ... Use HttpClient instead of webclient
using (HttpClient client = new HttpClient())
using (HttpResponseMessage response = await client.GetAsync(requestUrl))
using (HttpContent content = response.Content)
{
string mydata = await content.ReadAsStringAsync();
Regex regex = new Regex("href[\\s]*=[\\s]*\"(.*?)[\\s]*\\\"");
foreach (Match htmlPath in regex.Matches(mydata))
{
// Here you can write your custom logic
Console.WriteLine(htmlPath.Groups[1].Value);
}
}
}
Code explanation
Regex regex = new Regex("href[\\s]*=[\\s]*\"(.*?)[\\s]*\\\"");
This line will create regex object with given regular expression
you can find regex explanation Here after posting given regular expression
foreach (Match htmlPath in regex.Matches(mydata))
{
This line will iterate through all the matches found using regex in given string.
Console.WriteLine(htmlPath.Groups[1].Value);
Notice (.*?) in regex its capture group
Above line will give you your contains inside that group in your case data inside href brackets

FormUrlEncode returns unexpected result encoding the º(masculine ordinal indicator)

I have a program that comunicates with an external http server to the request a first, second etc value... (1º,2º,3º,4º,...)
I have an issue in c# with the º character.
Here is some example code:
var testdata=new Dictionary<string,string>{
{"val","º"},
{"val1","\xBA"},
{"val2","\u00BA"},
};
var content = new FormUrlEncodedContent(testdata);
var cont = content.ReadAsStringAsync().GetAwaiter().GetResult();
the result is:
val=%C2%BA&val1=%C2%BA&val2=%C2%BA
I test the communication with the server with curl and firefox console
and the result should be:
val=%BA&val1=%BA&val2=%BA
Somehow the extra %C2 in C# dosent work with the server.
How can I fix or escape the º correctly?

This issue relates with the default encoding used by FormUrlEncodedContent which is UTF-8 and your server expect ISO-8859-1.
Here is a workaround to get over it but you'll need (unfortunately) to add System.Web to your project :
// This is an implementation of FormUrlEncodedContent with `ISO-8859-1`
public class FormIso8859Encoder : ByteArrayContent
{
public FormIso8859Encoder(IEnumerable<KeyValuePair<string, string>> nameValueCollection)
: base(FormDataToByteArray(nameValueCollection))
{
Headers.Add("Content-Type", "application/x-www-form-urlencoded");
}
private static byte[] FormDataToByteArray(IEnumerable<KeyValuePair<string, string>> nameValueCollection)
{
StringBuilder sb = new StringBuilder();
foreach (var nameValue in nameValueCollection)
{
if (sb.Length > 0)
sb.Append('&');
sb.Append(nameValue.Key);
sb.Append('=');
// Here is the major change
sb.Append(HttpUtility.UrlEncode(nameValue.Value, Encoding.GetEncoding("iso-8859-1") ));
}
return Encoding.Default.GetBytes(sb.ToString());
}
}
Then
var testdata=new Dictionary<string,string>{
{"val","º"},
{"val1","\xBA"},
{"val2","\u00BA"},
};
var content = new FormIso8859Encoder(testdata);
var cont = content.ReadAsStringAsync().GetAwaiter().GetResult();
This provide the following output :
val=%BA&val1=%BA&val2=%BA

The correct unicode character for ° is \u00B0. More info can you find here how to work with unicode in C#.
All unicode characters can be found here.

How to search a downloaded string of a website?

I have downloaded the string and found the index but am not able to get the text which I am searching for. Here is my code:
System.Net.WebClient client = new System.Net.WebClient();
string downloadedString = client.DownloadString("http://www.gmail.com");
int ss = downloadedString.IndexOf("fun");
string mm = downloadedString.Substring(ss);
textBox1.Text = mm;

try the following
if (downloadedString .Contains("fun"))
{
// Process...
}

Visiting www.gmail.com will perform 3 directs. Try the following url instead:
https://accounts.google.com/ServiceLogin?service=mail&passive=true&rm=false&continue=https://mail.google.com/mail/&ss=1&scc=1&ltmpl=default&ltmplcache=2
Also, consider using a proper HTML Parser like the HTML Agility Pack.

Equivalent of Python code in C#?

I have to really ask this question as I donot know Python.
Following are a few lines taken from this place. I would appreciate if someone guides me in translating the following to C#
#Step 1: Get a session key
servercontent = myhttp.request(baseurl + '/services/auth/login', 'POST',
headers={}, body=urllib.urlencode({'username':username, 'password':password}))[1]
sessionkey = minidom.parseString(servercontent).getElementsByTagName('sessionKey')[0].childNodes[0].nodeValue
print "====>sessionkey: %s <====" % sessionkey

I can't translate it to C#, but I can explain what this code does:
Login to baseurl + '/services/auth/login' using the username and password provided.
Read the contents of that URL.
Parse the content for the first <sessionkey> tag, and read the value of its first child node.

Here's a quick-n-dirty translation:
using System.Linq.Xml;
using System.Net;
using System.Collections.Generic;
using System.Web;
// ...
var client = new WebClient();
var parameters = new Dictionary<string, string>
{
{ "username", username },
{ "password", password }
};
var result = client.UploadString(String.Format("{0}/services/auth/login", BaseUrl), UrlEncode(parameters));
var doc = XDocument.Load(result); // load response into XML document (LINQ)
var key = doc.Elements("sessionKey").Single().Value // get the one-and-only <sessionKey> element.
Console.WriteLine("====>sessionkey: {0} <====", key);
// ...
// Utility function:
private static string UrlEncode(IDictionary<string, string> parameters)
{
var sb = new StringBuilder();
foreach(var val in parameters)
{
// add each parameter to the query string, url-encoding the value.
sb.AppendFormat("{0}={1}&", val.Key, HttpUtility.UrlEncode(val.Value));
}
sb.Remove(sb.Length - 1, 1); // remove last '&'
return sb.ToString();
}
This code does a check to see that the response only has one sessionKey element, otherwise it'll throw an exception if there's 0, or more than 1. Then it prints it out.