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++?
Related
I'm working on a programming problem in C++, where I need to write a CSV parser. I've written this before for files, but the instructions state:
Input is provided as CSV format via STDIN. The first line is a header. The subsequent lines are data.
Here's an example of the input "file":
#id,time,amount
0,4,5
2,8,3
8,1,2
...
Now I'm a bit confused by this because I haven't worked with STDIN much since picking up C++ a few years ago. How exactly does one read in a csv file through STDIN? When I've used std::cin in the past, if I try to paste multiple lines, only the first line will get read.
The instructions of the programming problem did not make it clear how the input "file" will be fed in through STDIN, or perhaps there's some classical way it's done and my lack of knowledge makes me think it's unclear? Is there some standard way a CSV file is read in through STDIN?
All I am tasked to do is to process what comes through STDIN, and I'm not given how things are passed into STDIN. I feel like I need to know how things are passed in to know what I'm supposed to do? Like it could be passed in character by character, line by line, entry by entry, or the entire file at a time?
My program has different options: You can read a binary file or a text file, but you can the binary file option and choose a text file... How can I do to detect that you have introduced a incorrect file while I'm doing this
while(fich.read((char *)&struct,sizeof(struct)))
How can I do to detect that you have introduced a incorrect file while I'm doing this
The simple answer is: You cannot.
It's impossible to distinguish plain (let's say ASCII encoded) text files from binary files.
Any of the introductory byte sequences read from the file might be valid for both.
The silly but common solutions for this problem are:
give your file name an extension that implies a particular format
let your file have a magic byte sequence (1-2 bytes) in the beginning and imply a particular format
I'm beginning to feel awkwardly stupid, but I have a problem with outputting binary data to a file.
I have a file, let's say, 1000 bytes long. What I would like to do, in C++, is simply opening the file, replace ONE byte in a given position (let's say, the i-th byte), and close it.
File before operation:
AAAAAA
File after operation:
AAABAA
What is the easiest way to do so? I tried to open it with a ofstream.open, with the following modes:
ios::binary|ios::out
ios::binary|ios::app
ios::binary|ios::ate
All of these affected the actual size of the file after the operation. What should I do? I'm beginning to feel desperate.
Thank you very much and merry christmas to everybody!
Matteo
Besides binary mode, you need to open it in out and in modes. This corresponds to the fopen mode "r+b" which opens a file for reading and writing, and doesn't truncate the file if it exist (in fact, it must exist or you will fail to open the file).
References:
std::basic_filebuf::open
std::fopen
I am writing a C++ program which reads lines of text from a .txt file. Unfortunately the text file is generated by a twenty-something year old UNIX program and it contains a lot of bizarre formatting characters.
The first few lines of the file are plain, English text and these are read with no problems. However, whenever a line contains one or more of these strange characters mixed in with the text, that entire line is read as characters and the data is lost.
The really confusing part is that if I manually delete the first couple of lines so that the very first character in the file is one of these unusual characters, then everything in the file is read perfectly. The unusual characters obviously just display as little ascii squiggles -arrows, smiley faces etc, which is fine. It seems as though a decision is being made automatically, without my knowledge or consent, based on the first line read.
Based on some googling, I suspected that the issue might be with the locale, but according to the visual studio debugger, the locale property of the ifstream object is "C" in both scenarios.
The code which reads the data is as follows:
//Function to open file at location specified by inFilePath, load and process data
int OpenFile(const char* inFilePath)
{
string line;
ifstream codeFile;
//open text file
codeFile.open(inFilePath,ios::in);
//read file line by line
while ( codeFile.good() )
{
getline(codeFile,line);
//check non-zero length
if (line != "")
ProcessLine(&line[0]);
}
//close line
codeFile.close();
return 1;
}
If anyone has any suggestions as to what might be going on or how to fix it, they would be very welcome.
From reading about your issues it sounds like you are reading in binary data, which will cause getline() to throw out content or simply skip over the line.
You have a couple of choices:
If you simply need lines from the data file you can first sanitise them by removing all non-printable characters (that is the "official" name for those weird ascii characters). On UNIX a tool such as strings would help you with that process.
You can off course also do this programmatically in your code by simply reading in X amount of data, storing it in a string, and then removing those characters that fall outside of the standard ASCII character range. This will most likely cause you to lose any unicode that may be stored in the file.
You change your program to understand the format and basically write a parser that allows you to parse the document in a more sane way.
If you can, I would suggest trying solution number 1, simply to see if the results are sane and can still be used. You mention that this is medical data, do you per-chance know what file format this is? If you are trying to find out and have access to a unix/linux machine you can use the utility file and maybe it can give you a clue (worst case it will tell you it is simply data).
If possible try getting a "clean" file that you can post the hex dump of so that we can try to provide better help than that what we are currently providing. With clean I mean that there is no personally identifying information in the file.
For number 2, open the file in binary mode. You mentioned using Windows, binary and non-binary files in std::fstream objects are handled differently, whereas on UNIX systems this is not the case (on most systems, I'm sure I'll get a comment regarding the one system that doesn't match this description).
codeFile.open(inFilePath,ios::in);
would become
codeFile.open(inFilePath, ios::in | ios::binary);
Instead of getline() you will want to become intimately familiar with .read() which will allow unformatted operations on the ifstream.
Reading will be like this:
// This code has not been tested!
char input[1024];
codeFile.read(input, 1024);
int actual_read = codeFile.gcount();
// Here you can process input, up to a maximum of actual_read characters.
//ProcessLine() // We didn't necessarily read a line!
ProcessData(input, actual_read);
The other thing as mentioned is that you can change the locale for the current stream and change the separator it considers a new line, maybe this will fix your issue without requiring to use the unformatted operators:
imbue the stream with a new locale that only knows about the newline. This method may or may not let your getline() function without issues.
Hello I want to read from a text file full of directory contents
Here's my example:
below is my text file called MyText.txt
MyText.txt
title.txt,image.png,sound.mp3
I want to be able to read that .txt extension not the filename and I want it to be for file extensions only for example .txt or .mp3 how would I do that in c++?.
When I mean read I mean reference it in a if statement like this:
if(.mp3 exists in a text file)
{
fprintf(stderr,"sees the mp3 extensions");
}
I'm running Windows 7 32-bit.
I need a more cross platform approach.
May I suggest you to read a tutorial on C++ file handling and another one on C++ strings?
There is no a quick solution: you have to read the file using the ifstream class.
After reading the file and storing it in one or more strings, you can then use the find and substr string methods to create a queue of discrete filenames. Using the same methods, you can then split the queued elements again, in order to find the extensions and add them to a set. A set does not allow duplicates, so you are sure all the extensions will appear only once.