Best way to check string and convert to int in c#

Question

Please help me to improve my code. The idea is: if string is ok then convert to int

1- it does check just null or blank string

int t=0;
 if(!string.IsNullOrEmpty(textbox1.text.trim())
     t= int.Parse(textbox1.text.trim());

2-

if(int.tryparse(textbox1.text.trim(), out t)      
   t=int.Parse(textbox1.text.trim());

or shortif

 return string.IsNullOrEmpty(textbox1.text.trim()) ? 0 :  int.Parse(textbox1.text.trim());

is there other better way?

Answer 1

The correct way to get user input and convert it to integers is through the Int32.TryParse method. This method has the advantage to not throw a costly exception if the input is wrong (like Parse or Convert.ToInt32) but returns true or false allowing you to display a meaningful error message to your user.

int t;
if(Int32.TryParse(textbox1.Text, out t)
{
  // t has ben set with the integer converted
  // add here the code that uses the t variable
}
else
{
  // textbox1.Text doesn't contain a valid integer
  // Add here a message to your users about the wrong input....
  // (if needed)
}

Notice that textbox1.Text is never null so you don't need to explicitly check for it. Of couse I assume that this textbox1 is a TextBox control defined in your InitializeComponent call and thus is not null by itself.