Question

This seems like it should be easy, which is why it is driving me especially insane. Hopefully someone out there will see the problem right off. I’m just trying to build arrays from an array built from a user input. It seems to create an array that is bigger than the one I meant for it to. Here’s the program:

    int main()
{

  ifstream inFile;
  ofstream outFile;

  int numReq, fileSize;
  string lang, dash;

  char fileName[40];
  char confirm[10];
  char confirm2[10];
  int character;
  char year[3];
  char month[1];
  char day[1];
  char hour[1];


  cout << "What file to process?" << endl;
  cin >> fileName;

  year[0] = fileName[14];
  year[1] = fileName[15];
  year[2] = fileName[16];
  year[3] = fileName[17];

  cout << "year = " << year << "." << endl;

  month[0] = fileName[18];
  month[1] = fileName[19];

  cout << "month = " << month << "." << endl;
  cout << "so I gotta know, what is..." << endl;
  cout << "month[0]? " << month[0] << endl;
  cout << "month[1]? " << month[1] << endl;
  cout << "month[2]? " << month[2] << endl;
  cout << "month[3]? " << month[3] << endl;
  cout << "month[4]? " << month[4] << endl;
  cout << "month[5]? " << month[5] << endl;
  cout << "month[6]? " << month[6] << endl;


  day[0] = fileName[20];
  day[1] = fileName[21];

      cout << "day = " << day << "." << endl;

  hour[0] = fileName[23];
  hour[1] = fileName[24];

  cout << "hour = " << hour << "." << endl;

  cout << "so, 'fileName[23]' is = " << fileName[23] << "?" << endl;
  cin >> confirm;

  cout << "So, the year is " << year << ", the month is " << month
       << ", the day is " << day << ", the hour is " << hour << "?" << endl;
  cin >> confirm;

  //cout << "Is this what you chose? " << fileName << endl;                           
  //cin >> confirm;                                                                   
  //cout << "Which character to manipulate?" << endl;                                 
  //cin >> character;                                                                 

  //cout << "This one? " << fileName[character] << endl;                              
  //cin >> confirm2;                                                                  

  inFile.open(fileName);
  assert (!inFile.fail());


  outFile.open("revisedPracticeFile1.txt");

  outFile << fixed << showpoint; // I have no idea what this is...                    
  outFile << setprecision(2);    // .. or this for that matter.                       

  cout << "Processing data" << endl;

  inFile >> lang;

  while (!inFile.eof() ){
    if (lang.length() <= 2){

      outFile << lang << " ";


      // I should keep in mind, that, for whatever reason, it seemed like the         
      //item 'setw(6)' made the program work when I put it in, but didn't seem        
      //to make the program stop working when I took it out. Curious..                

      inFile >> dash >> numReq >> fileSize;

      outFile << numReq << " " << fileSize << endl;

    }
    else{
      inFile >> dash >> numReq >> fileSize;
          cout << "took out " << lang << " " << numReq << " " << fileSize << endl;
    }

    inFile >> lang;
  }
  inFile.close();
  //assert(!inFile.fail());                                                           
  outFile.close();

  return 0;
}

…And, this is what happens when I run the program:

    What file to process?
projectcounts-20090101-010000                                      
year = 2009.
month = 01009.
so I gotta know, what is...
month[0]? 0
month[1]? 1
month[2]? 0
month[3]? 0
month[4]? 9
month[5]? 
month[6]? 
day = 011009.
hour = 0111009.
so, 'fileName[23]' is = 0?
yes
So, the year is 1009, the month is 11009, the day is 111009, the hour is 0111009?
^C

… So what gives?

Answer 1

The syntax char year[3]; declares an array with 3 element. But, then you use it to store 4 elements. There are similar issues with your other arrays.

Also, you’re using char arrays as strings. That’s a C (not C++) way to do things. Of course you’re allowed to do this if you want. But, these c-style strings use the convention that the last item is a zero.

Thus, if you wanted a C-style string to store the work ‘foo’, you could do it like this

char string[10];  // anything bigger than 3 works
string[0] = 'f';
string[1] = 'o';
string[2] = 'o';
string[3] = '\0';  // this zero tells functions like `printf` that the string has ended.

Without that last zero, functions like printf will just keep outputting memory locations until it happens upon a zero somewhere.

EDIT: Consider using c++ std::string for your string processing.