Is there a output in textIO signature to write integers to a file? output only writes vectors, outputsstring writes substrings and output1 writes only characters. My problem with not using vectors is I have to write each integer into a line in the output file.
I am having tough time with SML.
Thank You.
To write an int to a file as a string, just convert it to a string using Int.toString and then write the string to the file.
To write a number to a file as a byte, use BinIO instead of TextIO. As the name suggests TextIO is for dealing with text - not binary data.
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I have a dataset, a ".inp" format file, and I need to read this file in c++. However, the fopen() fread() method seemed to fail and read the wrong data(e.g. the first integer should be 262144, the fread yields an integer much larger than this nevertheless).
To be more specific, my ".inp" file contains a few integers and float points, how can I read them successfully in c++?
enter image description here
This is the screenshot of the "*.inp" file from Notepad++. Basically this is a text file.
I solved it by coping the data into a txt. However, I am still not aware how to read "*.inp"
I found some info about INP file extension. It seems like there are multiple variances of it, each meant to be used for different purpose. Where is your file coming from? As for soultion, if you can't open the file using fopen/fstream normally, you could treat it as binary and read each value in the way you specify. Other than that, I could think of calling system functions to get file contents (like cat in linux for example), then if there are some random characters, you could parse your string to ommit them.
Here is example of how to call cat in C++:
Simple way to call 'cat' from c++?
I have a file with .dat extension which contains some binary data.i want to convert this to readable text format in c++.Read data line by line .
You have tried this way?
Read / Write Binary Data.
You can now iterate the data in the buffer and cast them to a char.
Now you can
write the chars.
Depending on your encoding the binary data will be "some char".
Linebreaks mostly are '10 or '13'.
myfile<<hashdugumu[key].numara;
I have this piece of code.For example,i would like to write to eighth line.How do i do that in c++ ?Thanks in advance.
If the line you want to write is exactly the same length (in bytes, not in characters, remember some encodings (like e.g. UTF-8) is variable length) then it's very easy: Just skip over the first seven lines and then write the line.
There is a caveat with this though: input streams and output streams have different stream positions. So if you read from a combined input/output file stream then only the read position will change, so if you just try to write directly then you will not write at the same position. To solve this you need to get the read position, and set the write position to the same value.
As an alternative, or if the data you want to write is not the same size as the existing data, then you have to use a temporary "buffer", be it another file or an actual in-memory buffer.
If the file is not big you can use an in-memory buffer, for example using a std::vector for the lines. Read each line into the vector, and then modify the lines (elements in the vector) that you want to modify. Finally reopen the file for writing, truncating it, and then just write each "line" to the file.
There is a slight problem with the above though when it comes to the rewriting of the data, and that is if the file is truncated and then there's an error when you write to the file, you can lose data. This can be dsolved by using a temporary file.
Using a temporary file it's easier to not bother with the in-memory buffer, and instead read from the original file and write directly to the temporary file. Knowing when you should write something else is done by keeping track of the current line numbers, which is easy if you read one line at a time. In your example you read the first seven lines from the original file and write them to the temporary file, after the seventh line you write your special eight line while skipping the original eight line from the original file, and then just continue reading/writing the remaining lines. When done close the files and then rename the temporary file as the original file.
I need to read a large file of either text, binary, or combination, such as a JPEG file, encrypt it, and write it to a file. At some later time I will need to read the encrypted data, and decrypt it.
The end goal is to verify that the decrypted data matches the original data.
My problem is that with large files greater than 1Meg, I don't want to read and write character by character. I am targeting this code for a phone and I/O will cause too long a delay for the user.
With a pure text file, using fread() and fwrite() convert the data to binary, and the result is different than the original. With a jpeg image, it appears that there is some textual content mixed in with the binary data.
Is there a way to efficiently read in an arbitrary type of file and write it back in the original format?
Or is character by character the only option?
Or am I still out of luck?
After debugging it turned out that the decrypt function had the plain text and cipher text buffers assigned backwards. After swapping the buffer assignments, the decrypted results matched the original data. I originally thought that maybe reading the text as binary and then rewriting as binary would not appear as text, but I was wrong.
Reading the entire file as binary works just fine.
suppose a text file has 11001100 11001101
and i open the text file and take the input from the file as pt[0]=11001100, pt[1]=11001101..
but if i take the input from file as in>>pt it wont put it in two different arrays which is obvious but it takes the whole line . Thus I have to take another for loop and traverse through the whole string and when I find a null character i start putting into the second array . But how can I do it without putting it into a variable and traversing .. I mean directly from the file itself ..
Read it one byte at a time (e.g. with fread()). Append each byte to pt[i], where i is incremented when a space is encountered.