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

Int32.Parse()

Int32.Parse (string s) method converts the string representation of a number to its 32-bit signed integer equivalent. When s is a null reference, it will throw ArgumentNullException. If s is other than integer value, it will throw FormatException. When s represents a number less than MinValue or greater than MaxValue, it will throw OverflowException.

string s1 = "1234";

string s2 = "manish";

string s3 = null;

string s4 = "123456789123456789123456789123456789123456789";

int result;

result = Int32.Parse(s1); //-- 1234

result = Int32.Parse(s2); //-- FormatException

result = Int32.Parse(s3); //-- ArgumentNullException

result = Int32.Parse(s4); //-- OverflowException

 

Int32.TryParse()

Int32.TryParse(string s, out int result) method converts the specified string representation of 32-bit signed integer equivalent to out variable, and returns true if it is parsed successfully, false otherwise. When s is a null reference, it will return 0 rather than throw ArgumentNullException. If s is other than an integer value, the out variable will have 0 rather than FormatException. When s represents a number less than MinValue or greater than MaxValue, the out variable will have 0 rather than OverflowException. 
 

string s1 = "1234";

 string s2 = "manish";

 string s3 = null;

 string s4 = "123456789123456789123456789123456789123456789";

 int result;

 bool success;

 success = Int32.TryParse(s1, out result); //-- success => true; result => 1234

 success = Int32.TryParse(s2, out result); //-- success => false; result => 0

 success = Int32.TryParse(s3, out result); //-- success => false; result => 0

 success = Int32.TryParse(s4, out result); //-- success => false; result => 0

 

Convert.ToInt32()

Convert.ToInt32(string s) method converts the specified string representation of 32-bit signed integer equivalent. This calls in turn Int32.Parse () method. When s is a null reference, it will return 0 rather than throw ArgumentNullException. If s is other than integer value, it will throw FormatException. When s represents a number less than MinValue or greater than MaxValue, it will throw OverflowException.
 

string s1 = "1234";

string s2 = "manish";

string s3 = null;

string s4 = "123456789123456789123456789123456789123456789";

int result;

result = Convert.ToInt32(s1); //-- 1234

result = Convert.ToInt32(s2); //-- FormatException

result = Convert.ToInt32(s3); //-- 0

result = Convert.ToInt32(s4); //-- OverflowException