I face an ofstream problem and the program cannot open the file that I want to write. The minimal, complete and varifiable code is showed as follows:
#include <cstdio>
#include <fstream>
using namespace std;
int main(){
string root_path = "E:\\160818\\";
string file_path = root_path + "haar_data.txt";
ofstream haar_file(file_path.c_str());
if(!haar_file) // < -------- File cannot be open
{
cout<<"Error opening file for writing\n";
return 1;
}
haar_file.close();
return 0;
}
My compiler is VS2008. The output in the screen is
Error opening file for writing.
What is the error? I want open this file to write something.
I have compiled your code and used it, it worked.
Note that you haven't included iostream in your provided code therefore I had to add it because of the 'cout' expression.
Note that since c++11 you don't need to use .C_str() to open a file.
Note that if your file doesn't exist, because you use ofstream (opens with ios::out), your file will be created anyway.
Are you using admin rights?
Is your path correct (folder name mistake?)
Related
Before you flag this as a duplicate post and refer me on how to correctly open a text file and print to the console, I have looked at numerous StackOverflow posts about this topic and cannot find a solution for myself.
I am trying to open a text file I created (currently in the same project folder as my main.cpp), read the text, and print it to the console. I go through the if file is open statement fine but the while loop does not go through even once. I will post the function below. Please suggest any changes or ideas on how to correctly call and open/read the text file. (and I would prefer not to call the exact file location of the text file for this to work ex. C://example/textFile.txt/ Though I have not tried this method yet, I'd prefer avoiding it)
Also, I am using CLion IDE from jetbrains, C++17, and Ninja to build.
printing text file to console fucntion
#include <iostream>
#include <iomanip>
#include <iomanip>
#include <fstream>
#include <string>
#include <stdlib.h>
#include "printTest.h"
void printTest::print() {
std::string line; //string that holds the line of a text file
std::ifstream textFile("test.txt", std::ios::in); //file creation
if(textFile.is_open()) //checking if file was opened
{
while(std::getline(textFile, line))
{
//std::getline(textFile, line);
std::cout << line << "\n";
}
} else { //this is always printing i.e. file is not correctly being opened for reading
std::cout <<"Unable to open the text file..." <<std::endl; //Prints if file was not opened
}
textFile.close();
}
I have a .txt file and I tried using the absolute path "C:\Users\(full path)\A3Data" and static paths (shown in code):
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
using namespace std;
int main()
{
string line;
ifstream MyReadFile("A3Data.txt");
if(MyReadFile.is_open()) //checks whether file is being opened
{
while (getline(MyReadFile, line)) //uses getline to get the string values from the .txt file to read line by line
{
cout << line << '\n';
}
MyReadFile.close();
}
else if (MyReadFile.fail())
{
cout << "A3Data.txt failed to open" << endl;
}
return 0;
}
Expected output:
(contents in A3Data.txt)
Actual Output:
"A3Data.txt failed to open"
Double backslashing the absolute path e.g. C:\\Users\\(full path)\\A3Data.txt gives me the error too.
Changing the filepaths and ifstream-ing it to the different path also shows me the error.
When i tried to read my file from cmd, I cd'ed it to the full path and typed in the text file name. I could open & read it properly. Hence I feel that the w.r.x are accessible to me and I have rights to the file.
UPDATE:
I have figured out my issue. Thank you all for the answers!
You need to double backslash or declare your file path as a string literal. You can do this like:
string myPath = L"C:\Users\(full path)\A3Data.txt";
As a string literal, or
string myPath = "C:\\Users\\(full path)\\A3Data.txt";
As a properly escaped file path
If the above does not work and you have guaranteed that you have the proper paths to the file then you may not have proper rights to the file. You could try running a command line as administrator and then executing your code from that, if that also fails let us know.
I have searched for this around the web and here but I can't seem to figure out what I am doing wrong.
I am simply trying get better with file processing and c++.
For practice I am trying to grab a text file from a game folder and make a copy of it.
Here is my code (that can't access the file).
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
int main()
{
//define / open files
ifstream my_input_file;
ofstream my_output_file;
string filepath = "C:/Users/David Laptop/Documents/my games/oblivion/RenderInfo.txt";
my_input_file.open(filepath);
if (my_input_file.is_open())
{
cout << "opened\n";
my_output_file.open("output_file.txt", ofstream::trunc);
char c;
my_input_file.get(c);
while (my_input_file)
{
my_output_file.put(c);
my_input_file.get(c);
}
my_input_file.close();
my_output_file.close();
}
else
{
cout << "FAIL\n";
}
cin.get();
return 0;
}
This seemed to work with both text files and .ini files when in the project directory but I am having issues properly getting to other directiorys?
Any ideas?
thanks!
Your code is perfectly valid and it works - I tried it with my own file instead of yours, in the line
string filepath = "C:/Users/David Laptop/Documents/my games/oblivion/RenderInfo.txt";
So you have not such file or it is not in the given path or you have not such path.
Correct it in that line and it will be OK.
Tip: Find your file in Windows Explorer, press (and keep pressing) Shift) and right-click on this file. From the context menu then choose Copy as path and then paste it to your code. But be carefull - you have to change every backslash (\) to a forward slash (/) (as in your code) or use double backslashes (\\) instead of a single one.
Can anyone tell me what is wrong with this code? I always get not open.
#include <iostream>
#include <fstream>
using namespace std;
int main(){
fstream fs;
fs.open("fsfile2",ios::in|ios::out|ios::binary);
if(fs.is_open()){
fs.write("wow",sizeof("wow"));
char str[20];
fs.read((char*)str,sizeof(str));
cout<<str<<endl;}
else
cout<<"Not open\n";
return 0;
}
Try this code
fs.open("fsfile2", ios::app|ios::in|ios::out|ios::binary);
By using the open() like you are that file will not be created if that is your goal.
If you want to create a new file please look at: fstream won't create a file
If the file exists, you are not looking for it in the right path. Or change the file name to the full path or put the executable in the folder where the file is.
Hope this helps.
Probably, you do not have permissions to create files in the directory, where your executable is.
Solution:
Please add a file extension to the filename.
If it's a text file, it will be
"fsfile2.txt"
Then, I tried removing
ios::in
since the first process only writes to file, and by removing that, the file is created and "wow" is also written at it.
In order for these lines
fs.read((char*)str,sizeof(str));
cout<<str<<endl;
to work,
You need to close the stream after writing to it, then open the stream in read mode, then read the contents. Take note that closing the stream will save the edited file.
Additional:
You can also change
fs.write("wow",sizeof("wow"));
to
fs << "wow";
You can do the same when reading from file,
fs >> str;
You can also use the string class of C++, instead of char array so that the number of characters inside the file won't be your problem anymore.
#include <string>
string str;
Checking for EOF (end-of-file) is recommended since files are read line by line. Once you add a new line and add a character to the line, the code that doesn't loop until EOF will only read the first line of the file.
In order to solve this, it is recommended to loop until EOF is reached.
while(!fs.eof()) {
fs >> str;
cout << str << endl;
}
So here is the improved snippet:
#include <string>
fs.open("fsfile2.txt", ios::out); // ios::out for write only
if(fs.is_open()) {
// writes "wow" to file
fs << "wow";
// closes the file
fs.close();
// ios::in for read only
fs.open("fsfile2.txt", ios::in);
// better to define variable just before using it
string str;
// loops until end-of-file
while(!fs.eof()) {
// reads a line from file, stores it to str
fs >> str;
// shows str to screen
cout << str << endl;
}
}
*Note: I removed
ios::binary
Since your code is not dealing with binary files yet.
I tried these and it worked fine! Have a nice day!
fstream fs; does not create a new file for you.
You need to make sure that the file exists in your project directory.
On the other hand, if you were to use ofstream fs("file.txt"); it would create the file for you. Or use only ios::out when you open fstream fs, this will create the file for you.
I have this code that suppose to read a txt file.
But for some reason i am always getting *File not found that means that fileIn.fail() failed...
#include <iostream>
#include <string.h>
#include <fstream>
#include <sstream>
#include <stdio.h>
using namespace std;
int main ()
{
string fileName;
ifstream fileIn;
bool x;
cout << "enter file name \n";
cin >> fileName;
fileIn.open(fileName);
if(fileIn.fail())
{
cerr << "* File not found";
return true;
}
the file located in the same folder as my main.cpp file and named input.txt. I have tried to set the fileName hard coded but this also didn't work.
What is wrong with my code?
here is the project:
Here is a checklist:
Do you have permissions to read/access the file?
Are you the owner of the file?(Linux)
Are you giving the correct path, relative or absolute from the executable?
If the answer to any of these is a no, then that is where the problem lies, not just "file not found" error.
--EDIT--
#VladIoffe the executable I see there, is qustion2 and the relative path you have to give is ../input.txt and not input.txt
You should use absolute path to the fileName.
Absoulut path will always works. But I hate full path I prefer relative path for a simple reason: code is more portable.
If you run your program with input.txt in the same path of executable it will work. But when you use an IDE you must set the current directory in the IDE settings.