Input file failed to open

[frogs777]

my input file is failing to open, any ideas?

#include <fstream>
#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;


int main()
{
using namespace std;
ifstream in_stream;
ofstream out_stream;

in_stream.open("C:\Documents and Settings\Administrator\Desktop\HW\HW4\hw4pr2input.txt");

if (in_stream.fail())
{
cout << "Input file opening failed.\n";
system ("pause");
exit(1);
}

out_stream.open("hw4pr2input_output");
if (out_stream.fail())
{
cout << "Output file opening failed.\n";
system ("pause");
exit(1);
}

int first, second, third;
in_stream >> first >> second >> third;
out_stream << "the sume of the first 3\n"
<< "numbers in the input\n"
<< "is" << (first + second + third)
<< endl;
in_stream.close( );
out_stream.close( );
return 0;
}

[Chervil]

Change each '\' to '\\' in this statement:
in_stream.open("C:\Documents and Settings\Administrator\Desktop\HW\HW4\hw4pr2input.txt");

'\' is used to denote an escape sequence such as '\n' for newline, so to represent an actual '\' character you must put '\\'.

[frogs777]

When I change the characters to '\\', the code continues to fail to open. Using code:blocks to build if that matters

[Drakon]

Does the file exist?
Or do you just need to create a file? How do you know it isn't opening?

Read: http://www.cplusplus.com/doc/tutorial/files/ and see if your code matches the example.

#include <iostream>
#include <fstream>
using namespace std;

int main () {
  ofstream myfile;
  myfile.open ("example.txt");
  myfile << "Writing this to a file.\n";
  myfile.close();
  return 0;
}

[frogs777]

the file does exist, at the location listed on C drive. The code as follows executes if the file fails to open

if (in_stream.fail())
{
cout << "Input file opening failed.\n";
system ("pause");
exit(1);
}

I am receiving "Input file opening failed" upon code execution indicating it is not opening

[Duthomhas]

We understand that much, but you have provided very little information.

Presuming you have checked that
(1) The file path is correct
(2) All \s are written as \\
(3) There are no non-ASCII characters in the filename or anything else that is messing with it
(4) The file does, in fact, exist before the program runs

Then I think you ought to check the file permissions. Does your program have access rights to open a file on your desktop? Does another process have the file opened or locked in some way?

[frogs777]

thank you I will check into permissions. The reply was in response to Drakon's response "How do you know it isn't opening?"

I am wondering if code snippets is the culprit in code blocks now

[Drakon]

I just tried a primitive cutdown version of this code, it worked fine for me. It may or may not be the answer for you but add

if (in_stream.fail() == true)
{
cout << "Fail";
}

I know .fail() returns a bool value, but I am checking it against one anyway to see if it is right or not.

I if \\ fails try using / I am not sure if that will work, but whenever I make programs that deal with files I build them then run the file from the debug/release folder.

[frogs777]

interesting, okay thanks

[Dy7SLyTq]

while your code is valid Drakon, there are shortcuts that do the samething that make it easier to read. because every condition is resolved to either true (and thusly will execute) or false (and the code will be skipped). so you could actually do if(in_stream.fail()) which is the same as your condition. lets say you wanted to test if it returned false (ie in_stream.fail() == false) that can be short cutted to if(!in_stream.fail()).

[Drakon]

lets say you wanted to test if it returned false (ie in_stream.fail() == false) that can be short cutted to if(!in_stream.fail()).

I knew of this method, and I like the smallness of it, but I have to ague for my eyesight I nearly missed the "!'' at the start of your code, thus why I tend to do things the "long" way.

But now I will try when I am explaining code give more than the way I do it.

Thanks :)

[Dy7SLyTq]

oh no if thats your way thats fine. if you cant see it (and maybe its just this text not saying you have bad eyesight) then you can write it that way. its just good to know for when you have long conditions