在C＃中检查字符串并将其转换为int的最佳方法

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.

Answer 2

int t = 0;
int.TryParse(textbox1?.Text?.Trim(), out t);

Answer 3

int i = 0;

Int32.TryParse(TextBox1.Text, out i);

Answer 4

Yes. We need to Check whether TryParse returns true or Not. if true then it succeeds & false if any error occurs.The TryParse will return 0 for both if the TryParse is failed or actual string value is 0.

string s2 = "13.3";
int i;

//i = Convert.ToInt32(s2);                   // Run Time Error
Console.WriteLine(int.TryParse(s2, out i));  // False
Console.WriteLine(i);                        // Output will be 0

string s3 = "Hello";
//i = Convert.ToInt32(s2);                  // Run Time Error
Console.WriteLine(int.TryParse(s3, out i)); // False
Console.WriteLine(i);                       // Output will be 0

string s1 = null;
Console.WriteLine(int.TryParse(s1, out i));  // False
Console.WriteLine(i);                        // Output will be 0

string s4 = "0";      
Console.WriteLine(int.TryParse(s4, out i));  // return True
Console.WriteLine(i);                        // Output will be 0