I have a simple struct containing some stuff, and also a Text field. I was looking at the result of encoding this data using Capnp, and for some reason the value of the text field appears in the encoded output twice! That doesn't seem very efficient or sane. Why does this happen?
Cap'n Proto does not encode text fields twice. To understand what happened in your case, we'd need to see your code.
Related
The query comes as
"returnData": [
"zWCLtKpUXZbkWNM9deAVPizTxXASOjX63ubdUHDN+vw=",
"zWCLtKpUXZbkWNM9deAVPizTxXASOjX63ubdUHDN+vw="
],
How can I decode that string? I can see it is decodable base64 first, but I get a very weird string after. Can someone show me the steps to follow to receive the decoded final string?
Base64 encodes binary data, which means if you send data that is not a string you won't be able to retrieve a string back. So to properly parse the return data you will need to know what data types were actually returned.
It might also be helpful to use a base64 to hex decoder first, so you get the hex representation of your data.
To give you more concrete recommendations we would need to know what data you expected, preferably showing the whole endpoint definition as well as any custom structs that might be involved.
I scraped some text from the internet, which I put in an UTF8String. I can use this string normally, but when I select some specific characters (strange character with accents, like in my case รบ), which are not part of the UTF8 standard, I get an error, saying that I used invalid indexes. This only happens when the string contains strange characters; my code works with normal string that do not contain strange characters.
Any way to solve this?
EDIT:
I have a variable word of type SubString{UTF8String}
When I use do method(word), no problems occur. When I do method(word[2:end]) (assuming length of at least 2), I get an error in case the second character is strange (not in UTF8).
Julia does indexing on byte positions instead of character position. It is way more efficient for a variable length encoding like UTF-8, but it makes some operations use some more boilerplate.
The problem is that some codepoints is encoded as multiple bytes and when you slice the string from 2:end you would have got half of the first character (witch is invalid and you get an error).
The solution is to get the second valid index instead of 2 in the slice. I think that is something like str[nextind(str, 1):end]
PS. Sorry for a less than clear answer on my phone.
EDIT:
I tried this, and it seems like SubString{UTF8String} and UTF8String has different behaviour on slicing. I've reported it as bug #7811 on GitHub.
For example, it prints below string:
"user_description" = "\U5efa\U5b50\Uff0c\U6b4c\U540e\Uff0c\U5c0f\U5e86\Uff0c\U5c0fKen\Uff0c\U8fd9\U4e9b\U90fd\U662f\U6211\U3002\U6211\U60f3\U505a\U7684\U5c31\U662f\Uff0c\U6253\U5f00\U53cc\U624b\Uff0c\U62e5\U62b1\U4f60\U3002";
any one know how to print the actual string instead these un-readable characters?
or do you know why this issue happen? how to avoid it? encoding?
I'm not sure how you print it out, or what type of string it is, but have you played with different types of format specifiers? Apple Doc
I have a form bean with attributes id, desc and imageByteArray. Struts action gets executed and it redirects to a JSP where i want to access these bean attributes like id, desc and convert the imageByteArray and display it as an image. I tried this post, but that's not working for me.
I encode the bytearray using Base64 - where this.bean.imageByteArray refers to the form bean
this.bean.setImageByteArray(new org.apache.commons.codec.binary.Base64().encode(imageInByteArr));
I tried this, but not working
<img src="data:image/jpg;base64,<c:out value='${bean.imageByteArray}'/>" />
Byte array (byte[] imageByteArray) refers a base64 encoded JPG image and I'm getting the following img tag as output and obviously nothing gets displayed,
<img src="data:image/jpg;base64,[B#2e200e">
Any idea how to convert base64 byte array and display as an image in JSP?
What you get is just the toString output of an array. You need however the byte array converted to a String.
You should create a method in bean
public String getByteArrayString()
{
return new String(this.imageByteArray);
}
and reference this in your JSP.
While technically you should define which encoding to use for an array of base64 bytes this is not necessary as all characters are in the standard 7bit ASCII range.
DoubleMalt's answer (accepted at the time of writing) is unfortunate, because it's sort of using two wrongs to make a right. It doesn't help that Apache Commons Codec makes it so easy to do the wrong thing :(
Base64 is fundamentally an encoding from binary data to text - as such, it should almost always be used to convert a byte[] to a String. Your issue is that you're converting a byte[] to another byte[] - but you later want to use that data as a string. It would be better to convert once, in the right way.
Now you can choose exactly when you convert to base64 (and a string). You could do it early, in your Java code, in which case I'd use:
// Obviously you'd need to introduce a new method for this, replacing
// setImageByteArray
this.bean.setImageBase64(new Base64().encodeToString(imageInByteArr));
<img src="data:image/jpg;base64,<c:out value='${bean.imageBase64}'/>" />
Alternatively, you could keep just the binary data in your bean, and the perform the encoding in the JSP. It's been a long time since I've written any JSPs, so I'm not going to try to write the code for that here.
But basically, you need to decide whether your bean should keep the original binary data as a byte[], or the base64-encoded data as a String. Anything else is misleading, IMO.
I have a number in Mathematica, a large number. I have even gotten this number in base 16 form, using OutputForm[]. I am basically trying to write out a number to a file in hex format.
Please keep in mind I am using 123456 in these examples instead of my 70,000 digit number.
Whenever I write a file using a simple Put[123456, "file.raw"] command, I get a raw data file with the actual data 3132333435360A with a line ending.
If I use Put[OutputForm[BaseForm[123456, 16]], "file.raw"] command, I get a raw data file with the data in hex format 31653234300A202020202031360A but still not written as raw data.
I would like the Hex Form of the Number Dumped as Data.
I have tried Export, BinaryWrite, and DumpSave, but can't figure it out.
I just am getting a headache I guess cause I can't see past what I need to do.
One thing I did try was doing:
Export["file.raw", 123456];
But the file is not raw enough. What I mean by that is there is there is header data and extra crap.
Would love to get this working thanks.
Please let us know what you expect to see in your output file, and what you want use it for. Do you want something a human can read, or something in a specified format to be used by a computer? Please provide an example.
The two examples using Put[] correctly provide files containing ASCII characters corresponding to the text representations of your inputs, and which are human-readable.
I think what you're looking for is IntegerString[_,16]:
In[33]:= IntegerString[123456, 16]
Out[33]= "1e240"
str = OpenWrite[];
WriteString[str, IntegerString[123456, 16]];
Close[str];
FilePrint[%]
1e240
(using WriteString instead of Put avoids having the string characters