C++: how can I write a program to read integers from a file?

When I use the code recommended in the book, I get an error. I am using NetBeans 6.8 for Mac.

Here is the code:

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

int main()
{

  ifstream in开发者_运维百科putFile;

  int number;

  inputFile.open("MacintoshHD/Users/moshekwiat/Desktop/random.txt");

  inFile >> number;

  cout<<endl <<number<<endl;

  inputFile.close();

  return (0);
}

Here is the error:

main.cpp:20: error: 'inFile' was not declared in this scope

What needs to be done?? Thank You

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Replace inFile with inputFile.

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Problem 1 (the one the compiler sees) is a simple typo: inFile should be inputFile. Do make sure you check for typos like this before posting to Stack Overflow.

Problem 2: the path name to your file is probably wrong, and generally, when you try to read from a stream that couldn't be initialized properly because the file couldn't be opened, you'll get 0.

In this case the path you specified is a relative path to the file from the directory your program was launched in, so whatever directory you ran the program from would need a subdirectory called "MacintoshHD", then "Users", then... you get the idea. To get the correct path, right-click on the file in the Finder and select "Get Info". Under "Where: " you'll see the correct path to the directory that contains your file; it will probably say "/Users/moshekwiat/Desktop". Add "/random.txt" to that and that should be the path you use.

Normally, C++ programmers will write code to make sure the file opens correctly before reading from it. A simple way to check for that after initializing inputFile, but before trying to read from it is:

if (! inputFile) {
    cerr << "Could not open the file!" << endl;
    return 1; // returning non-0 status is customary
              // if your program encounters an error
}

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Change inFile to inputFile

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For a start, there's no 'inFile' object in your code.

inFile >> number;

Look again:

ifstream inputFile;

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change inFile to inputFile

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Use inputFile instead of inFile