New to C++ Builder 10.4. Migrating from XE4.
A line of code fopen() that works fine in the old environment
InputFileHandle = fopen(FileName, "rb");
does not return a valid pointer in the FMX 3D environment for a file in the same directory that the project is running.
I'd appreciate if you can give me a solution for that.
Try to for check which error occur
#include <errno.h>
....
FILE *InputFileHandle;
if ((InputFileHandle = fopen(FileName, "rb")) == NULL)
printf(" %s \n", strerror(errno));
I can see only two possible trouble:
Permission error, you'll have to fix the file permission.
file does not exist meaning your new framework change the current directory.
Thank you PHE for the answer and the clue you posted for my question. I checked the permissions on the file and they are accessible as needed. The issue was the "change of current directory" and that was causing the file not to be recognized. One solid answer is to specify the path to the file from the root directory( this could be cumbersome for long file paths!). For windows path to be recognized you shall specify forward-slash twice in the related string to be decoded properly, like this "C://dir1//dir2//....//filename". Regards
Thank you PHE for the answer and the clue you posted for my question. I checked the permissions on the file and they are accessible as needed. The issue was the "change of current directory" and that was causing the file not to be recognized. One solid answer is to specify the path to the file from the root directory( this could be cumbersome for long file paths!). For the windows path to be recognized you shall specify backward-slash twice in the related string to be decoded properly, like this "C:\dir1\dir2\....\filename". Regards
Related
I am currently working on a project where I need to read windows events .
I am using OpenEventLog() and ReadEventLog() from Win API. I can read the events from system using the typename of the event.
But I need to specify the file name or file path of the .evtx file that I have saved from the EventViewer.I tried the below code,
HANDLE logHandle = OpenEventLog(NULL, "C:\\Users\\MyAccount\\Documents\\myevents.evtx");
DWORD status = GetLastError();
if(logHandle == NULL){
cerr<<"NO HANDLE GENERATED!!!"<<endl;
}else if(status == ERROR_INVALID_HANDLE){
cerr<<"INVALID HANDLE!!!"<<endl;
}else if(status!=0){
cout<<"OPENEVENTLOG ERROR STATUS::>"<<status<<endl;
}
But it does not find the specified file and switches over to default Application Events. Can anyone please tell me what the problem could be? or if there is anything to be changed in the code?
PS: I even tried placing the file in project folder and specifying just the filename(myevents.evtx) , but still doesn't work.I also tried reading the evtx directly as shown in "Reading .evt/.evtx files directly" , but later I found this can't be done. Apparently there is no way to read them directly without win API or without writing a whole bunch of parser code.
Thanks in advance.
Well, it turns out OpenEventLog() is not meant for opening saved .evtx files.
I should've been using OpenBackupEventLog() for that.
I am attempting to create an addon for Node.js that (among other things) writes content to a file inside my C++ class using ofstream.
std::ofstream license_file;
std::string fileContent(*NanAsciiString(args[0]));
license_file.open(PATH);
//file doesn't yet exist, so create it
if(!license_file) {
printf("ERROR: %s (%s)\n", strerror(errno), PATH);
}
license_file << fileContent;
license_file.close();
This works fine if PATH is set to the same directory as my Node.js code (e.g. ./license.txt).
However, ofstream fails to open/create the file in question if it is located anywhere else. For example, using ~/license.txt does not work (note: I'm running OSX).
The error reported is always No such file or directory -- even after I physically create ~/license.txt.
Any ideas why this works in one directory but not others? If it were a permissions issue I would expect a different error message.
For the record, I've seen about 20 other SO questions about "ofstream fails to create file" but passing additional flags into open() has no effect. I have a feeling this is somehow related to running inside Node/V8.
I think the issue is that you need to find out the user directory in a different way than using ~.
Well this time I'm trying to write a program in C which recover deleted files from a disk, it could be an external disk, I have an idea than i had used before on linux, it is to open the disk as a kind of file and scaning the Headers and file footers of everything within the disk, the point is I'm not sure if there's allow on windows to open a disk as an File, basiclly I have the logic how to develope this program, but I'm not sure how to implement it on windows, anybody can give me a hand with this?.
The code I used on linux to open a disk as a file was:
Edit: That was a sample of what I was using guys, it's just to give you an idea of what I was doing, the correct syntax I used was the next:
direccion = ui->linea->text().toLatin1().constData();
f = fopen(direccion,"rb");
I used QT creator on linux, and direccion variable was a TextField value which contained the file path of the disk through a button function that open a QFileDialog...
could I use it in windows as well?
Thank you before hand..
"The code I used on linux to open a disk as a file was:"
File *f = fopen("E:\", "rb");
I seriously doubt you ever got this code working on any linux system (or windows either).
You'll need to escape the backslash path delimiter, if it's presented in any string literal:
FILE* f = fopen("E:\\", "rb");
// ^
Also all that filesystem path style you are presenting to access a particular disk, is about accessing a windows file path/disk.
No linux file system has notion about drive characters, and the file path delimiter value used is '/', not '\\'.
To recover deleted files, you can't use fopen or fstream::open because the file was deleted. Check the return value from the function or test the stream state.
The way to recover deleted files is:
Get the Master File Table as raw data.
Search for the record containing a string similar to the deleted
filename.
Change the entry in the Master File Table to "undeleted".
Write the Master File Table back to the drive.
The above usually requires platform specific API, which is different on Linux and Windows platforms.
My programming knowlege is very limited so please take this into account when reading this. I am using Visual C++ MFC and I am looking for a basic function that would overwrite the contents of a file but keep the file the same name. I am sure this is probably fairly simple however I can't seem to find anything online. Thanks in advance for any help.
You can use CFile::Open() there is flags to specify to open an existing file without truncating it. For example if you want to create the file if it not exists, or using the alreading existing without truncating you can use CFile::modeCreate|CFile::modeNoTruncate. You can then seet to the needed position by using CFile::Seek()
It's been a while since I've done any MFC work so I'll just give you the general standard on how to do this in C/C++. This will give you a direction on how to work with MFC.
When you're opening a file, you can choose an "open flag" that tells the file system how to open it. it can be "a" for append, "r" for read, "w" for write over (trunacte), and you can add "b" if it's a binary file.
so to do that just do:
FILE *fp = fopen("my_file.whatever", "wb");
if (fp)
{
//now write to
the file... ....
fclose(fp);
}
Iam trying to get permissions on file/folder for current user. I found nice article about it here. I have tried to run this program but I got few erros and I dont know where I can find solutions to them. I tried to make my own version. Unfortunately when i try:
LPWSTR lpszPrimaryDC = NULL;
NetGetDCName(NULL, L"A", (LPBYTE *)&lpszPrimaryDC);
I got error: NERR_DCNotFound. How I can solve this problem?
The documentation says that error is returned when it "Could not find the domain controller for the domain specified in the domainname parameter." Do you have a domain called "A"? If not, the function is right to fail (and you need to rethink why/how you are calling it).
The only way the code didn't crash and gave me correct answer to question: is file or folder readable?
`
FILE *myFile = fopen(dirPath, "r");
if (myFile == 0) {
// "File or Dir is not readable
}
`
Hope this helps. You can use the same for writing test with "w".