System.FormatException: 'Input string was not in a correct format.'

Question

Input string was not in a correct format. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.FormatException: Input string was not in a correct format. Source Error: Line 42: SqlCommand cmd = new SqlCommand('insert into students(StudentName,Age) values(@StudentName,@Age)',con); Line 43: cmd.Parameters.AddWithValue('@StudentName',txtName.Text); Line 44: cmd.Parameters.AddWithValue('@Age',Convert.ToInt32(txtAge.Text)); Line 45: con.Open(); Line 46: int rows = cmd.ExecuteNonQuery(); Source File: C:\Users\ajayb\source\repos\WebApplicationpract7c\WebApplicationpract7c\InsertDelete.aspx.cs Line: 44

Tuhin Paul · Answer

The error "Input string was not in a correct format" occurs on Line 44 because txtAge.Text contains a value that cannot be converted to an integer using Convert.ToInt32() . This happens when: The age textbox is empty The user entered non-numeric text (e.g., "twenty", "abc") The input contains spaces, decimals, or special characters (e.g., "25.5", " 30 ", "30 years")

Amit Mohanty · Answer

The errror is triggered on this line: cmd.Parameters.AddWithValue("@Age", Convert.ToInt32(txtAge.Text)); That means txtAge.Text is not a valid integer at runtime. This can occur if: The field is left blank. The input contains non-numeric characters. The number is outside the valid Int32 range. So, before using, you should validate the input: int age; if (!int.TryParse(txtAge.Text, out age)) { // Handle invalid input (show message, default to 0, etc.) Response.Write("Please enter a valid number for age."); return; } But my recommendations is don’t use AddWithValue blindly. It can cause type mismatches. Use SqlDbType : int age; if (!int.TryParse(txtAge.Text, out age)) { // Handle invalid input (show message, default to 0, etc.) Response.Write("Please enter a valid number for age."); return; } cmd.Parameters.Add("@Age", SqlDbType.Int).Value = age; cmd.Parameters.Add("@StudentName", SqlDbType.NVarChar, 100).Value = txtName.Text;

System.FormatException: 'Input string was not in a correct format.'

Input string was not in a correct format.

Answers (2)