Question

I keep getting an error that I cannot figure out with the below VS2019 windows forms .net framework windows forms

error CS0029 C# Cannot implicitly convert type 'bool' to 'string' It appears to be this that is causing the issue

string id;
while (id = sr.ReadLine() != null)

using System;
using System.Collections.Generic;
using System.IO;
using System.Windows.Forms;

namespace Dropbox13
{
public partial class SearchForm : Form
{
private List allStudent = new List();
public SearchForm()
{
InitializeComponent();
}

private void SearchForm_Load(object sender, EventArgs e)
{

using (StreamReader sr = new StreamReader("student.txt"))
{
string id;
while (id = sr.ReadLine() != null)
{
string name = sr.ReadLine();
int score = int.Parse(sr.ReadLine());
//create a student oject
Student s = new Student(id, Name, score);
//add to the List
allStudent.Add(s);
}
}
}

Answer 1

//------------- SearchForm.cs
using System;
using System.Collections.Generic;
using System.IO;
using System.Windows.Forms;

namespace Dropbox13
{
    public partial class SearchForm : Form
    {   
        private List<Student> allStudent = new List<Student>();
        public SearchForm()
        {
            InitializeComponent();
        }

        private void SearchForm_Load(object sender, EventArgs e)
        {

            using (StreamReader sr = new StreamReader(@"D:\student.txt"))
            {
                string id;                
                while ( (id = sr.ReadLine()) != null ) //read id and if its not null then proceed
                {
                    string name = sr.ReadLine();
                    int score = int.Parse(sr.ReadLine());
                    //create a student oject
                    Student s = new Student(id, name, score);
                    
                    //add to the List
                    allStudent.Add(s);
                    Console.WriteLine( s.toString() );  //display student info to console
                }
            }

        }
    }
}
//-------------- end of SearchForm.cs


/*------------- student.txt
s1
Alan
60
s2
Bob
70
s3
Cary
80
------------- end of student.txt */


//-------------- Student.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Dropbox13
{
    class Student
    {
        private string id;
        private string name;
        private int score;

        public Student(string id, string name, int score)
        {
            this.id = id;
            this.name = name;
            this.score = score;
        }
        public string toString()
        {
            return id + " "+ name + " " + score;
        }
    }
}

//-------------- end of Student.cs

You just forgotten the braces as follows

while ( (id = sr.ReadLine()) != null ) //read id and if its not null then proceed

I have displayed the student details on console for testing..

thanks...

Output