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Posted 27 Jan 2009

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

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27 Jan 2009CPOL1 min read
Difference between Int32.Parse(), Convert.ToInt32(), and Int32.TryParse()

Introduction

Int32.parse(string)

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. For example:

C#
string s1 = "1234"; 
string s2 = "1234.65"; 
string s3 = null; 
string s4 = "123456789123456789123456789123456789123456789"; 

int result; 
bool success; 

result = Int32.Parse(s1); //-- 1234 
result = Int32.Parse(s2); //-- FormatException 
result = Int32.Parse(s3); //-- ArgumentNullException 
result = Int32.Parse(s4); //-- OverflowException 

Convert.ToInt32(string)

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. For example:

C#
result = Convert.ToInt32(s1); //-- 1234 
result = Convert.ToInt32(s2); //-- FormatException 
result = Convert.ToInt32(s3); //-- 0 
result = Convert.ToInt32(s4); //-- OverflowException 

Int32.TryParse(string, out int)

Int32.Parse(string, out int) 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. This method is available in C# 2.0. 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. For example:

C#
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 is better than Int32.Parse since it returns 0 rather than an exception. But again, according to the requirement, this can be used. TryParse will be the best since it always handles exceptions by itself.

History

  • 27th January, 2009: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Alfredo_Fernandez
Architect AgileWare
Brazil Brazil
15 years of software development

Comments and Discussions

 
GeneralMy vote of 2 Pin
silverghost00710-May-14 18:09
Membersilverghost00710-May-14 18:09 
QuestionMessage Closed Pin
27-Sep-13 17:12
MemberMember 1024450327-Sep-13 17:12 
AnswerRe: Benchmarks on Int.Parse(), Convert.ToInt32(), Int.TryParse() Pin
Alfredo_Fernandez7-Apr-16 9:10
MemberAlfredo_Fernandez7-Apr-16 9:10 
GeneralMy vote of 5 Pin
desenvolvedor8224-Jan-13 17:40
Memberdesenvolvedor8224-Jan-13 17:40 
GeneralMy vote of 5 Pin
ssa201018-Jul-12 20:27
Memberssa201018-Jul-12 20:27 
SuggestionNice Work AgilWare Pin
Thilina Chandima26-Mar-12 3:30
MemberThilina Chandima26-Mar-12 3:30 
GeneralRe: Nice Work AgilWare Pin
Not Active27-Mar-12 16:08
mentorNot Active27-Mar-12 16:08 
GeneralMy vote of 2 Pin
Amit Narula30-Nov-09 5:39
MemberAmit Narula30-Nov-09 5:39 
GeneralMy vote of 2 Pin
Stinky Boat18-Nov-09 13:20
MemberStinky Boat18-Nov-09 13:20 
GeneralExceptions are not necessarily bad Pin
Omer Mor28-Jan-09 6:22
MemberOmer Mor28-Jan-09 6:22 
GeneralMy vote of 2 Pin
Omer Mor28-Jan-09 6:16
MemberOmer Mor28-Jan-09 6:16 
GeneralUmm... Pin
PIEBALDconsult27-Jan-09 12:58
professionalPIEBALDconsult27-Jan-09 12:58 
GeneralSome comments Pin
Colin Angus Mackay27-Jan-09 6:27
MemberColin Angus Mackay27-Jan-09 6:27 
GeneralRe: Some comments Pin
supercat927-Jan-09 8:05
Membersupercat927-Jan-09 8:05 
GeneralRe: Some comments [modified] Pin
Colin Angus Mackay27-Jan-09 8:30
MemberColin Angus Mackay27-Jan-09 8:30 
GeneralRe: Some comments Pin
supercat927-Jan-09 9:26
Membersupercat927-Jan-09 9:26 
GeneralRe: Some comments Pin
Colin Angus Mackay27-Jan-09 11:27
MemberColin Angus Mackay27-Jan-09 11:27 
SuggestionRe: Some comments Pin
David A. Gray4-Sep-15 17:29
MemberDavid A. Gray4-Sep-15 17:29 
GeneralRe: Some comments Pin
Alfredo_Fernandez7-Apr-16 9:05
MemberAlfredo_Fernandez7-Apr-16 9:05 
GeneralRe: Some comments Pin
David A. Gray7-Apr-16 11:57
MemberDavid A. Gray7-Apr-16 11:57 
Since I covered a great deal of ground, it's hard to know how to respond to a broad statement like "I did not understand." Nevertheless, I hope that the following quotation from the MSDN library will clarify my intent and assumptions.

Quote:
When an exception occurs, it is passed up the stack and each catch block is given the opportunity to handle it. The order of catch statements is important. Put catch blocks targeted to specific exceptions before a general exception catch block or the compiler might issue an error. The proper catch block is determined by matching the type of the exception to the name of the exception specified in the catch block. If there is no specific catch block, the exception is caught by a general catch block, if one exists.


Source: How to: Use Specific Exceptions in a Catch Block[^]

In other words, if the last of a succession of Catch blocks catches a System.Exception, any exception not already caught will get caught, regardless of how specialized it happens to be. That includes OutOfMemory, DivideByZero, ArithmeticOverflow, and even the occasional unavoidable I/O exception.

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