I try to load a file with fstream. The code looks like this
file.open("../levels/level0.lvl");
if (file.is_open()) {
while (!file.eof()) {
std::getline(file, Str);
list = ReadLine(Str, list);
}
}
But it loads nothing. Yes only if the path is absolute.
How can I make the path relative?
The folder "levels" is hosted in the debug folder. same folder as the exe.
"The folder "levels" is hosted in the debug folder. same folder as the exe."
It doesn't matter in which position the levels folder is in relation to the executable's path.
The relevant folder to determine the relative path is the working directory where your executable is actually started from.
See here: fstream doesn't resolve path also.
Path handling is OS specific. The correct way to handle this is to add a way of the user specifying the path to your application and then use that path. For example, you could add a command line option --level-file=<path>. Then your program can read the path from that option and pass it to the fstream constructor.
See my answer to this question for more: https://stackoverflow.com/a/40980510/2345997
Related
I have tried to use QFile to open a text file:
I tried
QFile file("serial_deviceIP.txt");
but the file.open() returns false.
However, if I switched to a global address like:
QFile file("C:/Users/shupeng/Documents/qgroundcontrol_peidong_mod/serial_deviceIP.txt");
it works. Why? How can I solve this?
In the first instance, the path to the file cannot be found.
QFile file("serial_deviceIP.txt");
This specifies the file with a relative path, and will only work if serial_deviceIP.txt is in the current working directory, which is likely to be the directory that contains the executable of your program.
QFile file("C:/Users/shupeng/Documents/qgroundcontrol_peidong_mod/serial_deviceIP.txt");
This is referencing an absolute file path, so the file will be found
You can also use Qt's Resource System to bundle the files with your application.
Create a .qrc file in your project and add any file you wish to use/load in your application to it.
Then you can load your file as:
QFile file( ":myfiles/serial_deviceIP.txt" );
See QT Resource System for more information.
What happens is that when we are developing our code we usually keep our project source dir on mind as the reference so we don't give an absolute path, but after building the current directory will change and it will be the build directory, so our application won't find the files without a absolute path.
A possible solution is to add a Resources in our project including our project directory. So just add the following line in the project_file.pro:
RESOURCES += ./
and then use the character : before the file's name when you go to read it, like it:
QFile foo(":bar.txt")
That just work for read it but not for write. So to write is necessary specify an absolute path.
I'm trying to load files, and previously I was using hardcoded file locations, (like "c:\location\file.txt") but now that a few friends are also using the file, I'd like to allow them to put the executable wherever they want.
my current code looks like:
ifstream myfile;
myfile.open("c:\\client\\settings.cfg");
I'm trying to change it so that the user puts their executable into whatever folder they want, and then they create a folder and put their settings file into it and the exe will load that with their settings.
ifstream myfile;
myfile.open("\\settings\\settings.cfg");
I have some basic error handling in place, and now the program always errors out saying that it can't find the file.
The file structure looks like this:
[ART]
asset.png
[SETTINGS]
settings.cfg
client.exe
This seems like a really simple thing to do, but I can't find any way to do it. Every example and tutorial about reading and writing to files deals only with files in the executable's directory, or hardcoded into c:\folder...
Could anyone point me to how I do this?
The search path for most systems starts with the current working directory and then to a PATH environment variable. So, all you need to do is specify the file/folder without the absolute path markings and it will use the path relative to the working directory:
ifstream myfile;
myfile.open("settings\\settings.cfg");
// ^^ Note the lack of \\ to start the file path
Paths beginning with \ are always relative to the current drive's root directory. If the current drive is C:, then \settings\settings.cfg means C:\settings\settings.cfg.
Note that you can use / in order to avoid escaping everything. So you can use: settings/settings.cfg. This will be relative to the user's current directory. Note however, that this doesn't necessarily correspond to the directory where the executable resides. If you need the directory of the executable, then you need to use a Windows API function to get it:
#include <Windows.h>
// ...
HMODULE module = GetModuleHandleW(NULL);
WCHAR path[MAX_PATH];
GetModuleFileNameW(module, path, MAX_PATH);
Now if you want to open settings/settings.cfg relative to the directory of the executable, create a path that starts with path and append /settings/settings.cfg to it.
In the project i am working on, during run-time I need to open some file and read it
std::ifstream vSettings(".\\..\\..\\Data\\data.xml");
if (vSettings.good())
{
//file found ,work with it
}
I never get true for the good() call above.
Manually I checked that the file indeed exists relatively to the .exe.
the path to exe is \main\proj\bin\Debug-Win32.the path to file main\proj\Data.When running in the user computer the directory will be installed relatively to the .exe
I work in debug mode and path is as it looks from the "bin" directory point of view.
Any advises?
Go to the Debugging settings
and change the $(ProjectDir) to $(OutDir), and it should behave like you expect
File opens if I write the full path (full-path/roots.txt).
File fails to open if I write the filename only (roots.txt)
And yet, roots.txt is in the same folder as the main.cpp.
Is there any settings I should check on XCode?
Here's the code:
string line;
ifstream infile;
infile.clear();
// infile.open("roots.txt");
infile.open("/Users/programming/C++/roots/roots.txt");
if (infile.fail()) cout << "could not open the file: " << strerror(errno);
getline(infile, line);
cout << line;
By default, Xcode working directory is something like ~/Library/Developer/Xcode/DerivedData/project-/Build/Products/Debug. So,if you are trying to use a relative path with respect your project directory or any other, you should manually configure your working directory in Xcode.
You can do this by: Product -> Scheme -> Edit Scheme -> options tab, tick the use custom working directory checkbox and show your path.
If it works when you attempt to open a file with an absolute path and fails with just the filename, your relative path is likely incorrect. Ensure roots.txt is placed in the current working directory. Look into the getcwd function declared in unistd.h.
To change the working directory when you're running from inside XCode: select "Edit Active Executable" in your "Project" menu.
You can adjust your working directory settings at the bottom of the "General" section.
Assuming you're running file from within XCode, the working directory is unlikely to be the same directory where your .cpp file is located. Check what your current working directory is what you think it is. (you should be able to obtain it using a getcwd call)
I moved from Windows to Mac and now I'm experiencing a problem with the file input/output classes: ifstream & ofstream.
In Windows when you run with g++/Code Blocks
ofstream out("output.txt");
out << "TEST";
out.close();
A new file "output.txt" will be created in the same directory.
However in MAC OS X, this file is created in my home directory: /Users/USER_NAME/output.txt
How can I have this file in the same directory together with the executable?
P.S. I'm using GCC and CodeBlocks. There are no projects - I'm just compiling a single source file.
The stream classes, like all other file-opening functions, use the current directory when you provide a relative path. You can control the current directory with a function like chdir, but a better solution is to use fully qualified file names. Then you remove your program's dependency on the current directory.
The file is simply created in the current working directory. Change working directory or provide full path.
The working directory is initially set when your program starts. When you start it from the command line, you inherit the current working directory from the shell. In CodeBlock, one of the project options is the execution working dir' for debug runs.
(See also http://www.gamedev.net/community/forums/topic.asp?topic_id=571206&whichpage=1�)
You'll need to provide a full, absolute path to the file you are trying to create.