Program cannot open file, but the file is already there - c++

I am writing a program that will open an image file, but strange thing happened. This is the output from cmd:
C:\Users\Karl\Pictures>testcvconsole mypic.jpg
argv[0]==testcvconsole
argv[1]==mypic.jpg
fopen is null
strerror(errno)==No such file or directory
Are there something I should consider when fopen simply failed to open my file when the file is right there along side with the executable file in the same directory?
This is on Windows 7, Visual Studios Express 2010. C++.
EDIT: code below
#include "stdafx.h"
#include <string.h>
#include <errno.h>
int goMain(int argc, char** argv);
int _tmain(int argc, _TCHAR* argv[])
{
goMain(argc, (char**)argv);
return 0;
}
int goMain( int argc, char** argv ){
if (argv[1] != NULL){
printf("argv[0]==%S\nargv[1]==%S\n", argv[0], argv[1]);
if (fopen(argv[1], "r") == NULL){
printf("fopen is null\n");
printf(strerror(errno));
}
}
return 0;
}
EDIT2:
I have tried
char *workingDir =_getcwd(NULL, 0);
printf("workingDir == %S", workingDir);
as TomK has suggested and it returned:
workingDir ==
Nothing at all. Hmm...
EDIT3:
I am getting something. I tried
argv[1] = "C:/Users/Karl/Pictures/mypic.jpg";
And fopen can open it. This statement above is inserted right before the fopen.

Make absolutely sure they are in the same directory. I'm saying this because you're using Visual Studio, for which the "same" directory isn't always so clear, because it depends on how you execute the executable through the IDE.
C:\Users\Karl\Pictures>testcvconsole mypic.jpg
Are you sure mypic.jpg is located in C:\Users\Karl\Pictures ?

Can u check whether the working directory is correct?
#include <direct.h>
char *workingDir =_getcwd(NULL, 0);
Can you run your application with admin privileges?

Usually the .exe is created in sub-directory either Debug or Release - try giving the absolute path to the image ...

I've had this problem, and it turned out that Visual Studio's runtime wasn't setting the current directory. I never figured out the problem: instead I simply used an absolute path. Without the absolute path, your program is looking in C:\. You can also try using ".\\mypic.jpg" or GetCurrentDirectory().

Related

Cannot write an array in a Ubuntu device using C++ (Debug Assertion Failed. Expression (stream !=NULL))

I am working on Windows and I am trying to write an array into a Ubuntu device using C++ in Visual Studio 2019. Here's a sample of my code:
int Run_WriteCalibTable(char *pcIPAddress, int iNumArgs, float *fArgs, int *iAnsSize, char *sAns)
...
...
...
char pcFolderName[256];
char pcFileName[256];
sprintf(pcFolderName, "%s\\%s",pcSavePath, pcUUTSerialNumber);
sprintf(pcFileName, "%s\\calib_rfclock.conf",pcFolderName);
// WRITE TABLE ON PC
FILE *pFileW;
pFileW = fopen(pcFileName,"wb");
fwrite(&CalibTable, sizeof(char), CalibTable.hdr.v1.u32Len, pFileW);
fclose(pFileW);
}
return 0;
However, I keep having this pop-up from Microsoft Visual C++ Debug Library that says:
Debug Assertion Failed:
Program:...
File: f:\dd\vctools\crt_bld\sefl_x86\crt\src\fwrite.c
Line: 77
Expression: (stream != NULL)
...
I found this thread and I tried logging in as root on my Ubuntu device. I also tried:
mount -o remount,rw /path/to/parent/directory
chmod 777 /path/to/parent/directory
And I can also create/edit manualy any file in the directory I'm trying to write into with my code, but I get the same error when running it.
Anyone knows what could cause this? I think it could be on the Windows side, but I don't know what I am doing wrong. Thanks a lot in advance.
You never check that opening the file succeeds - and it most likely fails, which is why you get the debug pop-up. Your use of \ as directory delimiters may be the only reason why it fails, but you should check to be sure.
I suggest that you use std::filesystem::path (C++17) to build your paths. That makes it easy to create paths in a portable way. You could also make use of a C++ standard std::ofstream to create the file. That way you don't need to close it afterwards. It closes automatically when it goes out of scope.
Example:
#include <cerrno>
#include <cstring>
#include <filesystem>
#include <fstream>
int Run_WriteCalibTable(char *pcIPAddress, int iNumArgs, float *fArgs,
int *iAnsSize, char *sAns)
{
...
// Build std::filesystem::paths:
auto pcFolderName = std::filesystem::path(pcSavePath) / pcUUTSerialNumber;
auto pcFileName = pcFolderName / "calib_rfclock.conf";
// only try to write to the file if opening the file succeeds:
if(std::ofstream pFileW(pcFileName, std::ios::binary); pFileW) {
// Successfully opened the file, now write to it:
pFileW.write(reinterpret_cast<const char*>(&CalibTable),
CalibTable.hdr.v1.u32Len);
} else {
// Opening the file failed, print the reason:
std::cerr << pcFileName << ": " << std::strerror(errno) << std::endl;
}
...
}

cstdio fopen and fclose not working correctly on osx

I'm using tinyxml through openframeworks which uses cstdio for file access. I can see the example program quite happily create and write files but there is no delete so my plan is to implement remove, but after trying to run this code in my own project it doesn't seem to create a file or notify me of an error.
This code runs as expected on windows, just not on mac osx 10.8.5, no file is generated.
#include <cstdio>
int main(int argc, const char * argv[])
{
bool bClosed = false;
bool bWritten = false;
FILE* testFile;
testFile = fopen(".\\test.xml", "w");
if(testFile)
{
bWritten = fputs("test writing.", testFile);
bClosed = !fclose(testFile);
}
return 0;
}
edit: i now know the file exists as can read from it, i just cant view it in finder, i have hidden files shown, its not found its way into the app's package contents.
On a unix-like system (e.g. Mac OS X and Linux) a Windows path as
".\\test.xml"
should rather be
"./test.xml"
Anyway the simplest solution for this case might just be
"test.xml"

Can not read text file with Qt 5

I wrote a simple code to open plain text file with Qt 5's QFile as seen below;
// main.cpp
#include <iostream>
using std::endl;
using std::cout;
#include <QCoreApplication>
#include <QFile>
#include <QIODevice>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QFile plainFile("plain.txt");
if(plainFile.open(QIODevice::ReadOnly | QIODevice::Text))
{
cout << "File opened successfull" << endl;
plainFile.close();
}
else{
cout << "could not open file." << endl;
}
return a.exec();
}
The output when compiled and run is "could not open file".
What am I do wrong?
Probably because plain.txt does not exist in the current working directory or in the PATH. Make sure the file is in the working directory or pass the absolute path to QFile.
Also see what QFile::exists returns.
Wouter Huysentruit is right.
Remember, that, by default, when you running application from QtCreator working directory is, for example, C:\Projects\build-Test-Desktop_Qt_5_1_0_MinGW_32bit-Debug. But your .exe file lay in C:\Projects\build-Test-Desktop_Qt_5_1_0_MinGW_32bit-Debug\Debug.
When you run your .exe directly, then working directory will be that folder, where this file is layed now.
So, you can:
1.Pass absolute path.
2.Put file in current working directory (I suppose that it is best solution).
3.Just change relative path: QFile plainFile("debug/plain.txt");

How to check if a file exists with stat in visual studio c++ 2010?

This is the code I have for checking if a file exists in my visual studio 2010 c++ project:
bool GLSLProgram::fileExists( const string & fileName )
{
struct stat info;
int ret = -1;
ret = stat(fileName.c_str(), &info);
return 0 == ret;
}
I am not sure why it returns false for "shaders/color.vert" when that file really exists, and shaders is a folder in my project main folder.
Can you see something wrong?
THanks
Ok, so to illustrate the quirks of running from the IDE here's a little test I did. Hopefully this should help you figure out how relative paths work in VS.
So my folder hierarchy looks like this:
/_Sandbox
_Sandbox.sln
/Debug
_Sandbox.exe
/shaders
color.vert
/_Sandbox
_Sandbox.proj
main.cpp
The code looks as follows:
#include <iostream>
#include <string>
#include <sys/stat.h>
int main(int argc, char* argv[])
{
struct stat info;
std::string path = "shaders/color.vert"; // To not I get the same behavior with "shaders\\color.vert"
int ret = stat(path.c_str(), &info);
ret == 0 ? std::cout << "File found." << std::endl : std::cout << "File doesn't exist." << std::endl;
std::cin.get();
return 0;
}
So if I run this in the IDE, I get "File doesn't exist.", if I run this outside the IDE, I get "File Found". In order for the program to find the shader file from inside VS I have to put the shader folder like so:
/_Sandbox
_Sandbox.sln
/Debug
_Sandbox.exe
/_Sandbox
/shaders
color.vert
_Sandbox.proj
main.cpp
You can however get the code to find the folder from inside and outside the IDE. What you have to do is go to your project's settings. In "Debugging" and change "Working directory" to $(SolutionDir)$(Configuration)\
Hopefully this clears things up for you.

c++ simpleini example on getting a ini file from a directory?

hi could someone help me i'm trying getting the liberty simpleini for c++ to read/write a file from a different directory but so far nothing is working.
using windows 7
#include "SimpleIni.h"
#include <stdio.h>
int main( int argc, char** argv)
{
CSimpleIniA ini;
ini.SetValue("test", "default", "1");
ini.SaveFile("c:\\test\\test.ini");
//tried ini.SaveFile("c:\test\test.ini");
ini.LoadFile("c:\\test\\test.ini");
//tried ini.LoadFile("c:\test\test.ini");
const char * set = ini.GetValue("test", "default", "");
printf( "value = %s", set ); // should load from c:\test\test.ini
return 0;
}
source http://code.jellycan.com/simpleini-doc/html/index.html
The problem is in that it doesn't create directories.
You should create "c:\test" directory first on your own and then start application.
I started with your code and it didn't work, then I created "test" folder on drive C and it began to.