Difference among int.Parse,Convert.ToInt32 and int.TryParse

Introduction

This tip presents the main difference between int.Parse(), Convert.ToInt32() and int.TryParse().

1. int.Parse(string s)

2. Convert.ToInt32(string s)

3. int.TryParse(string s,Out)

int.Parse(string s)

Simply, int.Parse (string s) method converts the string to integer. If string s is null, then it will throw ArgumentNullException. If string s is other than integer value, then it will throw FormatException. If string s represents out of integer ranges, then it will throw OverflowException.

Example

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//
// int.Parse(string s)
//
class Program
    {
        static void Main(string[] args)
        {
            string str1="9009";
            string str2=null;
            string str3="9009.9090800";
            string str4="90909809099090909900900909090909"; 
            int finalResult;
            finalResult = int.Parse(str1); //success
            finalResult = int.Parse(str2); // ArgumentNullException
            finalResult = int.Parse(str3); //FormatException
            finalResult = int.Parse(str4); //OverflowException 
        }
    } 

Convert.ToInt32(string s)

Simply, Convert.ToInt32(string s) method converts the string to integer. If string s is null, then it will return 0 rather than throw ArgumentNullException. If string s is other than integer value, then it will throw FormatException. If string s represents out of integer ranges, then it will throw OverflowException.

Example

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//
// Convert.ToInt32(string s)
//
class Program
    {
        static void Main(string[] args)
        {
            string str1="9009";
            string str2=null;
            string str3="9009.9090800";
            string str4="90909809099090909900900909090909"; 
            int finalResult;
            finalResult = Convert.ToInt32(str1); // 9009
            finalResult = Convert.ToInt32(str2); // 0
            finalResult = Convert.ToInt32(str3); //FormatException
            finalResult = Convert.ToInt32(str4); //OverflowException 
        }
    }

int.TryParse(string s,Out)

Simply int.TryParse(string s,out int) method converts the string to integer out variable and returns true if successfully parsed, otherwise false. If string s is null, then the out variable has 0 rather than throw ArgumentNullException. If string s is other than integer value, then the out variable will have 0 rather than FormatException. If string s represents out of integer ranges, then the out variable will have 0 rather than throw OverflowException.

Example

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//
// Convert.ToInt32(string s)
//
class Program
    {
        static void Main(string[] args)
        {
            string str1="9009";
            string str2=null;
            string str3="9009.9090800";
            string str4="90909809099090909900900909090909"; 
            int finalResult;
            bool output;
            output = int.TryParse(str1,out finalResult); // 9009
            output = int.TryParse(str2,out finalResult); // 0
            output = int.TryParse(str3,out finalResult); // 0
            output = int.TryParse(str4, out finalResult); // 0 
        }
    }

Finally, among all these methods, it is better to use int.TryParse(string s, out int) as this method is the best forever.