C# Convert.ToInt64(String, IFormatProvider)用法及代碼示例

此方法用於使用指定的區域性特定格式信息將數字的指定字符串表示形式轉換為等效的64位帶符號整數。

用法:

public static long ToInt64 (string value, IFormatProvider provider);

參數：

value:它是一個包含要轉換的數字的字符串。
provider:它是提供區域性特定格式信息的對象。

返回值：此方法返回一個十進製數字，該數字等於value中的數字；如果value為null，則返回0(零)。

異常：

FormatException：如果該值不包含一個可選的符號，後跟一個數字序列(0到9)。
OverFlowException：如果該值表示一個小於MinValue或大於MaxValue的數字。

以下示例程序旨在說明Convert.ToInt64(String，IFormatProvider)方法的用法：

範例1：

// C# program to demonstrate the 
// Convert.ToInt64() 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 long value"
                    + " from a specified string "); 
  
        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 long 
    long val = Convert.ToInt64(s, cultures); 
  
    // display the converted long value 
    Console.Write(" {0}, ", val); 
} 
}

輸出：

Converted long value from a specified string  12345,  12345,  -12345,

範例2：對於FormatException

// C# program to demonstrate the 
// Convert.ToInt64() 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 long 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 
        long val = Convert.ToInt64(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 long value 
    long val = Convert.ToInt64(s, cultures); 
  
    // display the converted 
    // decimal value 
    Console.Write(" {0}, ", val); 
} 
}

輸出：

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

format of s is invalid 
Exception Thrown:System.FormatException

範例3：對於OverflowException

// C# program to demonstrate the 
// Convert.ToInt64() 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 long 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 long 
        long val = Convert.ToInt64(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 long value 
    long val = Convert.ToInt64(s, cultures); 
  
    // display the converted long value 
    Console.Write(" {0}, ", val); 
} 
}

輸出：

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

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

參考：

https://docs.microsoft.com/en-us/dotnet/api/system.convert.toint64?view=netframework-4.7.2#System_Convert_ToInt64_System_String_System_IFormatProvider_

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