If you've got a string, and you expect it to always be an integer (say, if some web service is handing you an integer in string format), you'd use Int32.Parse(). If you're collecting input from a user, you'd generally use Int32.TryParse(), since it allows you more fine-grained control over the situation when the user enters invalid input. Convert.ToInt32() takes an object as its argument. (See Chris S's answer for how it works) Convert.ToInt32() also does not throw ArgumentNullException when its argument is null the way Int32.Parse() does. That also means that Convert.ToInt32() is probably a wee bit slower than Int32.Parse(), though in practice, unless you're doing a very large number of iterations in a loop, you'll never notice it.

Int32.parse(字符串)——>

Int32。Parse (string s)方法将数字的字符串表示形式转换为等效的32位有符号整数。当s是空引用时，它将抛出ArgumentNullException。如果s不是整数值，则抛出FormatException。当s表示一个小于MinValue或大于MaxValue的数字时，它将抛出OverflowException。例如:

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

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

Convert.ToInt32(字符串)——> 转换。ToInt32(string s)方法将指定的字符串表示形式转换为等效的32位有符号整数。这将依次调用Int32。Parse()方法。当s是空引用时，它将返回0而不是抛出ArgumentNullException。如果s不是整数值，则抛出FormatException。当s表示一个小于MinValue或大于MaxValue的数字时，它将抛出OverflowException。

例如:

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

没有区别。 Convert.ToInt32()在内部调用int.Parse()

除了一件事Convert.ToInt32()当参数为空时返回0

否则两者的工作方式是一样的

转换。ToInt32允许空值，它不会抛出任何错误 Int。解析不允许空值，它会抛出ArgumentNullException错误。

int。Parse (string s)

RANGE >中的整数返回整数值 空值> argementnullexception 格式不是> FormatException 值不在RANGE > OverflowException

转换。ToInt32(字符串)

RANGE >中的整数返回整数值 空值>返回“0” 格式不是> FormatException 值不在RANGE > OverflowException

bool isParsed = int。TryParse（string s，out res）

RANGE中的整数>返回整数值，isParsed = true 空值>返回“0”，isParsed = false 不是格式>返回"0"，isParsed = false 值不在RANGE >返回"0"，isParsed = false

试试.....下面的代码

class Program
{
    static void Main(string[] args)
    {
        string strInt = "24532";
        string strNull = null;
        string strWrongFrmt = "5.87";
        string strAboveRange = "98765432123456";
        int res;
        try
        {
            // int.Parse() - TEST
            res = int.Parse(strInt); // res = 24532
            res = int.Parse(strNull); // System.ArgumentNullException
            res = int.Parse(strWrongFrmt); // System.FormatException
            res = int.Parse(strAboveRange); // System.OverflowException

            // Convert.ToInt32(string s) - TEST
            res = Convert.ToInt32(strInt); // res = 24532
            res = Convert.ToInt32(strNull); // res = 0
            res = Convert.ToInt32(strWrongFrmt); // System.FormatException
            res = Convert.ToInt32(strAboveRange); //System.OverflowException

            // int.TryParse(string s, out res) - Test
            bool isParsed;
            isParsed = int.TryParse(strInt, out res); // isParsed = true, res = 24532
            isParsed = int.TryParse(strNull, out res); // isParsed = false, res = 0
            isParsed = int.TryParse(strWrongFrmt, out res); // isParsed = false, res = 0
            isParsed = int.TryParse(strAboveRange, out res); // isParsed = false, res = 0 
        }
        catch(Exception e)
        {
            Console.WriteLine("Check this.\n" + e.Message);
        }
    }

If you've got a string, and you expect it to always be an integer (say, if some web service is handing you an integer in string format), you'd use Int32.Parse(). If you're collecting input from a user, you'd generally use Int32.TryParse(), since it allows you more fine-grained control over the situation when the user enters invalid input. Convert.ToInt32() takes an object as its argument. (See Chris S's answer for how it works) Convert.ToInt32() also does not throw ArgumentNullException when its argument is null the way Int32.Parse() does. That also means that Convert.ToInt32() is probably a wee bit slower than Int32.Parse(), though in practice, unless you're doing a very large number of iterations in a loop, you'll never notice it.