C# | Convert。FromBase64String(字符串)方法
原文:https://www . geeksforgeeks . org/c-sharp-convert-from base64 string-method/
此方法用于将指定的字符串转换为等效的 8 位无符号整数数组，该字符串将二进制数据编码为 64 位基数。
语法:
public static byte[] FromBase64String (string s);
这里， s 是要转换的字符串。
返回值:这个方法返回一个 8 位无符号整数数组，相当于的。
异常
- 参数空异常:如果 s 为空。
- 格式异常:如果 s 的长度，忽略空格字符，不是零或者 4 的倍数。或s的格式无效。 s 包含一个非 base-64 字符、两个以上的填充字符或填充字符中的一个非空白字符。
以下程序说明了转换的使用。FromBase64String(字符串)方法:
例 1:
// C# program to demonstrate the
// Convert.FromBase64String(String) Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// defining and initializing
// byte1 and byte2
byte[] byte1 = {2, 4, 6, 8, 10,
12, 14, 16, 18, 20};
byte[] byte2 = {10, 20, 30,
40, 50};
// calling get() Method
get(byte1, "byte1");
Console.WriteLine("");
get(byte2, "byte2");
}
catch (ArgumentNullException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
catch (FormatException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(),
e.Message);
}
}
// Defining get() method
public static void get(byte[] bytes, string str)
{
Console.WriteLine("For {0}", str);
// converting byte to base 64 string
string s = Convert.ToBase64String(bytes);
Console.WriteLine("The base 64 string: '{0}'", s);
Console.WriteLine("The base 64 string: '{0}'", s);
// converting base 64 string to byte array
byte[] val = Convert.FromBase64String(s);
Console.WriteLine("Converted byte value: {0}",
BitConverter.ToString(val));
}
}
Output:
For byte1
The base 64 string: 'AgQGCAoMDhASFA=='
The base 64 string: 'AgQGCAoMDhASFA=='
Converted byte value: 02-04-06-08-0A-0C-0E-10-12-14
For byte2
The base 64 string: 'ChQeKDI='
The base 64 string: 'ChQeKDI='
Converted byte value: 0A-14-1E-28-32
示例 2: 适用于参数异常
// C# program to demonstrate the
// Convert.FromBase64String(String) Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// defining and initializing
// byte1 and byte2
byte[] byte1 = {2, 4, 6, 8, 10, 12,
14, 16, 18, 20};
// calling get() Method
get(byte1, "byte1");
Console.WriteLine("");
// converting base 64 string to byte array
Console.WriteLine("s is null");
byte[] val = Convert.FromBase64String(null);
Console.WriteLine("Converted byte value: {0}",
BitConverter.ToString(val));
}
catch (ArgumentNullException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
catch (FormatException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
}
// Defining get() method
public static void get(byte[] bytes, string str)
{
Console.WriteLine("For {0}", str);
// converting byte to base 64 string
string s = Convert.ToBase64String(bytes);
Console.WriteLine("The base 64 string: '{0}'", s);
// converting base 64 string to byte array
byte[] val = Convert.FromBase64String(s);
Console.WriteLine("Converted byte value: {0}",
BitConverter.ToString(val));
}
}
Output:
For byte1
The base 64 string: 'AgQGCAoMDhASFA=='
Converted byte value: 02-04-06-08-0A-0C-0E-10-12-14
s is null
Exception Thrown: System.ArgumentNullException
例 3: 为格式异常
// C# program to demonstrate the
// Convert.FromBase64String(String) Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// defining and initializing
// byte1 and byte2
byte[] byte1 = {2, 4, 6, 8, 10,
12, 14, 16, 18, 20};
// calling get() Method
get(byte1, "byte1");
Console.WriteLine("");
// converting base 64
// string to byte array
Console.WriteLine("s contains a non-base-64 character");
byte[] val = Convert.FromBase64String("sun");
Console.WriteLine("Converted byte value: {0}",
BitConverter.ToString(val));
}
catch (ArgumentNullException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
catch (FormatException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
}
// Defining get() method
public static void get(byte[] bytes, string str)
{
Console.WriteLine("For {0}", str);
// converting byte to base 64 string
string s = Convert.ToBase64String(bytes);
Console.WriteLine("The base 64 string: '{0}'", s);
// converting base 64 string to byte array
byte[] val = Convert.FromBase64String(s);
Console.WriteLine("Converted byte value: {0}",
BitConverter.ToString(val));
}
}
Output:
For byte1
The base 64 string: 'AgQGCAoMDhASFA=='
Converted byte value: 02-04-06-08-0A-0C-0E-10-12-14
s contains a non-base-64 character
Exception Thrown: System.FormatException
参考:
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