C＃| Convert.ToInt32(String，IFormatProvider)方法

此方法用于使用指定的区域性特定格式信息将数字的指定字符串表示形式转换为等效的32位带符号整数。

句法：

public static int ToInt32 (string value, IFormatProvider provider);

参数：

• value：它是一个包含要转换的数字的字符串。
• 提供者：提供特定于区域性格式信息的对象。

返回值：此方法返回一个32位有符号整数，该整数等于value中的数字，如果value为null，则返回0(零)。

例外情况：

• FormatException ：如果该值不包含一个可选的符号，后跟一个数字序列(0到9)。
• OverflowException ：如果该值表示一个小于MinValue或大于MaxValue的数字。

下面的程序说明了Convert.ToInt32(String，IFormatProvider)方法的使用：

范例1：

// C# program to demonstrate the
// Convert.ToInt32() Method
using System;
using System.Globalization;
  
class GFG {
  
// Main Method
public static void Main()
{
    try {
  
        // creating object of CultureInfo
        CultureInfo cultures = new CultureInfo("en-US");
  
        // declaring and initializing String array
        string[] values = {"12345", "+12345",
                                   "-12345"};
  
        // calling get() Method
        Console.Write("Converted int value "
                    + "of specified strings: ");
  
        for (int j = 0; j < values.Length; j++) 
        {
            get(values[j], cultures);
        }
    }
  
    catch (FormatException e) 
    {
  
        Console.WriteLine("\n");
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }
  
    catch (OverflowException e) 
    {
  
        Console.WriteLine("\n");
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }
}
  
// Defining get() method
public static void get(string s,
           CultureInfo cultures)
{
  
    // converting string to specified int
    int val = Convert.ToInt32(s, cultures);
  
    // display the converted char value
    Console.Write(" {0}, ", val);
}
}

输出：

Converted int value of specified strings:  12345,  12345,  -12345,

示例2：对于FormatException

// C# program to demonstrate the
// Convert.ToInt32() Method
using System;
using System.Globalization;
  
class GFG {
  
// Main Method
public static void Main()
{
      
try {
  
    // creating object of CultureInfo
    CultureInfo cultures = new CultureInfo("en-US");
  
    // declaring and initializing String array
    string[] values = {"12345", "+12345",
                              "-12345" };
  
    // calling get() Method
    Console.WriteLine("Converted int value"
              + " of specified strings: ");
  
    for (int j = 0; j < values.Length; j++)
    {
  
        get(values[j], cultures);
    }
  
    Console.WriteLine("\n");
    string s = "123 456, 789";
  
    Console.WriteLine("format of s is invalid ");
  
    // converting string to specified char
    int val = Convert.ToInt32(s, cultures);
  
    // display the converted char value
    Console.Write(" {0}, ", val);
}
  
catch (FormatException e) {
  
    Console.Write("Exception Thrown: ");
    Console.Write("{0}", e.GetType(), e.Message);
}
catch (OverflowException e) {
  
    Console.Write("Exception Thrown: ");
    Console.Write("{0}", e.GetType(), e.Message);
}
}
  
// Defining get() method
public static void get(string s,
           CultureInfo cultures)
{
  
// converting string to
// specified int value
int val = Convert.ToInt32(s, cultures);
  
// display the converted int value
Console.Write(" {0}, ", val);
}
}

输出：

Converted int value of specified strings: 
 12345,  12345,  -12345, 

format of s is invalid 
Exception Thrown: System.FormatException

示例3：对于OverFlowException

// C# program to demonstrate the
// Convert.ToInt32() Method
using System;
using System.Globalization;
  
class GFG {
  
// Main Method
public static void Main()
{
      
    try {
  
        // creating object of CultureInfo
        CultureInfo cultures = new CultureInfo("en-US");
  
        // declaring and initializing String array
        string[] values = {"12345", "+12345",
                                  "-12345" };
  
        // calling get() Method
        Console.WriteLine("Converted int value "
                    + "of specified strings: ");
  
        for (int j = 0; j < values.Length; j++) 
        {
  
            get(values[j], cultures);
        }
  
        Console.WriteLine("\n");
        string s = "-7922816251426433759354395033500000";
  
        Console.WriteLine("s is less than the MinValue");
  
        // converting string to specified char
        int val = Convert.ToInt32(s, cultures);
  
        // display the converted char value
        Console.Write(" {0}, ", val);
    }
      
    catch (FormatException e) 
    {
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }
      
    catch (OverflowException e) 
    {
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }
}
  
// Defining get() method
public static void get(string s,
           CultureInfo cultures)
{
  
    // converting string to
    // specified int value
    int val = Convert.ToInt32(s, cultures);
  
    // display the converted int value
    Console.Write(" {0}, ", val);
}
}

输出：

Converted int value of specified strings: 
 12345,  12345,  -12345, 

s is less than the MinValue
Exception Thrown: System.OverflowException

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.convert.toint32?view=netframework-4.7.2#System_Convert_ToInt32_System_String_System_IFormatProvider_