如何确定字符串是否是Base64解码？ [英] How to determine if a string is Base64 decoded or not?

问题描述

如何确定字符串是否已被Base64解码？

How to determine if a string is Base64 decoded or not?

推荐答案

这样做：

Do it like this:

public bool IsBase64Encoded(String str)
{
    try
    {
        // If no exception is caught, then it is possibly a base64 encoded string
        byte[] data = Convert.FromBase64String(str);
        // The part that checks if the string was properly padded to the
        // correct length was borrowed from d@anish's solution
        return (str.Replace(" ","").Length % 4 == 0);
    }
    catch
    {
        // If exception is caught, then it is not a base64 encoded string
       return false;
    }
}

如果字符串str，该函数将返回true是Base64编码，如果不是，则为false。仍然存在疑问，因为包含随机字母和数字的字符串可能仍然看起来是Base64编码的，即使它只是一个随机字符串。在这种情况下唯一的好答案是假的，因为这会告诉你字符串绝对不是Base64编码的字符串。



干杯和快乐的编码！



-MRB

The function will return true if the string str was Base64 encoded and false if it was not. There is still is a doubt because a string that contains random letters and numbers might still look Base64 encoded even if it was just a random string. The only good answer in this case is false because that will tell you that the string is definitely not a Base64 encoded string.

Cheers and happy coding!

-MRB

我认为你的意思是编码，对吗？



使用 Convert.FromBase64String 方法。如果它抛出FormatException，则原始字符串不是base64。这样的事情：

I think you mean encoded, right?

Use Convert.FromBase64String method. If it throws FormatException, then the original string was not base64. Something like this:

public static bool IsBase64(string base64String){
if(base64String.Replace(" ","").Length % 4 != 0){
return false;
}

try{
Convert.FromBase64String(base64String);
return true;
}
catch(FormatException exception){
// Handle the exception
}
return false;
}

您可以在此方法中添加null check等，以减少异常。

You can add null check etc to this method to make it less exception prone.

你的意思是编码？



如果是这样，你可以在C＃中这样做：

Do you mean encoded?

If so, you can do it like this in C#:

try
{
   byte[] converted = Convert.FromBase64String(base64value);
   return base64value.EndsWith("=");
}
catch
{
   return false;
}

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