Difference between Int32.Parse(string), Int32.TryParse(string, out int) and Convert.ToInt32(string)

Hello Folks,

Today I am going to share with you guys my experiance with Casting methods. Which one to use and what is the

basic difference between them. I will discuss the difference between Int32.Parse(string), Int32.TryParse(string) and Convert.ToInt32(string)

and discuss on which to use

Int32.parse(string) and Convert.ToInt32(string) will either return value or throw exception.

Int32.TryParse(string, out int) will return true if conversion is success and false if not. And the converted value will be stored in 2nd parameter.

I will take a simple sample and display the behavior of these three methods. 

            string exp1 = null;

            string exp2 = "ASPDOTNETHACKER";

            string exp3 = "123";

            string exp4 = "12345678987654321";

Parameter Passed	Int32.Parse(string)	Int32.TryParse(string, out int)	Convert.ToInt32(string)
exp1	This will throw ArgumentNullException	This will return false and value 0 will be stored in int parameter	This will return 0
exp2	This will throw FormatException	This will return false and value 0 will be stored in int parameter	This will throw FormatException
exp3	This will convert string to int and retrun 123	This will convert string to int and return bool value. Value will stored in int parameter	This will convert string to int and retrun 123
exp4	The will throw OverflowException	This will return false and value 0 will be stored in int parameter	The will throw OverflowException

Now the million dollor question. which one to use.

Here goes the the order Int32.TryParse(string, out int) > Convert.ToInt32(string) > Int32.Parse(string)

Int32.Parse(string) does nothing for us unless we provide string representation of number. In all other case it throws exception. As one need to be extra careful while using Int32.Parse(string) avoid using it as far as possible.

Convert.ToInt32(string) is little better than Int32.Parse(string) as it shows some smartness to not throw exception if string is null and silently return 0. So Always prefer Convert.Int32(string) over Int32.Parse(string)

Int32.TryParse(string, out int) is the most robust and handle all the case and make sure no exception is thrown, whatever the case maybe. In other words this method is smartest of all. In fact I only use this method for casting purpose.