I have file.txt with this structure (in picture):
and I want to read this file and i'dont know if there is a methode to read file by column because when i get for exemple 25 from my file i need to know that it is the VEHICLE NUMBER.
I think use to lines to do this!! any idea please?
There is no function in C++ to read a file by column. You have to write your own function to do that.
A text file is stored on disk line-by-line, so you have to read the whole file line-by-line and on each line parse out the column data you are interested in.
Related
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 would like to open a file "my_query.sql" and read the entire text of that file into some macro variable x.
Clearly, I should start with something like:
file open myfile using my_query.sql
But my problem is that file read myfile x isn't quite right as that just reads the first line...
My initial ideas:
Perhaps there is a way to open it in binary and read the whole thing in with a single command?
Or do I have to do some hacked up, read the file line by line and concatenate the strings together?
My preferred solution is the "hacked up, read the file line by line and concatenate" solution.
I can also understand why the solution may seem hacked up, especially for somebody coming from a programming language. For example, this approach might even seem silly next to something like a BufferedReader in Java, but I digress...
You only get the first line of the file when you execute file read myfile x because, according to the documentation at help file:
"The file is positioned at the top (tof), so the first file read reads at the beginning of the file."
This is actually a convenience if you are writing to a file with file write because you won't have to embed newline characters in the string you wish to write - each call to file write will write a new line.
Now, there is a very simple loop construct that allows us to read line by line and store the contents into the macro.
So, if I had a .sql file at /path/to/my/file/ titled SqlScript.sql with the following contents:
SELECT *
FROM MyTable
WHERE Condition
Then the solution becomes something along the lines of:
clear *
file open myfile using "/path/to/my/file/SqlScript.sql", read
file read myfile line
local x "`line'"
while r(eof) == 0 {
file read myfile line
local x "`x'" " " "`line'"
}
file close myfile
di "`x'"
and the result:
SELECT * FROM MyTable WHERE Condition
Here, I used r(eof) to condition my while loop. This is an end of file marker which evaluates to 1 when file read reaches the end of the file.
Here's something that may help you open the file in binary and read it into a local macro.
The good news is, this appears to read the entire text file into the macro in one read.
clear *
file open myfile using "SqlScript.sql", read binary
file read myfile %100s line
local x "`line'"
file close myfile
di "`line'"
The bad news it, it (as written) reads 100 characters - it doesn't know where to stop. I think that if you know what signifies end-of-text-file on your operating system, you could search for that character and substring everything up to it. But dealing this this is beyond me at the moment. And you'll want to replace the newlines with spaces.
If this can be made to work for you I'd like to see the solution.
I have to extract information from a text file.
In the text file there is a list of strings.
This is an example of a string: AAA101;2015-01-01 00:00:00;0.784
The value after the last ; is a non integer value, which changes from line to line, so every line has different lenght of characters.
I want to map all of these lines into a structured vector as I can access to a specific line anytime I need without scan the whole file again.
I did some research and I found some threads about a command called, which permit me to reach a specific line of a text file but I read it only works if any line has the same characters lenght of the others.
I was thinking about converting all the lines in the file in a proper format in order to be able to map that file as I want but I hope there is a better and quick way
You can try TStringList*. It creates a list of AnsiStrings. Then each AnsiString can be accessed via ->operator [](numberOfTheLine).
So I have a txt file and I want to create a function to search through it and find a specific line. The txt file is a list of baby names and the frequency of the name being used. It looks like this:
jack,M,1456
julie,F,879
conner,M,540
ben,M,20843
Basically I want to have a function that will display the line of the name if the user inputs that name. So the user would be prompted to input a name, and I would use their input to search through the file until it finds the name. If julie were inputted by the user, the result would be the screen printing out julie,F,879.
Also, on that note, what if I had more than one txt file? For example:
file1.txt
jack,M,1456
julie,F,879
conner,M,540
ben,M,20843
file2.txt
jacob,M,15687
alex,F,5648
shannon,F,964
conner,M,760
How would I search through multiple txt files to find the line? If the user entered alex how would I get the function to search through two separate txt files?
And lastly (I know, this is dragging on..) If the user inputted conner, how would I get the program to display the lines from both txt files?
Thank you so much in advance for your help!
Just to give you a hint to start. You could use the stl ifstream class, where you can also extract formatted data. The stl gives you a lot of means to achieve what you want.
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.