Positioning in arrays, fstream, and char comparison - c++

Question

I am currently trying to do an assignment in my C++ class. I think I've gotten as far as I can on my own.
The assignment calls for me to read names from a text file, put the names in order, and write them to a new file.
The names in the given text file are formatted as follows:
Jackie Sam Tom Bill Mary Paul Zev Barb John
My code that I have for the assignment:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
string nameArray[26] = {};
int main() {
// Defined variables
int y = 65, lineNumber = 0;
string readName;
// Opens the text file LineUp
ifstream readfile;
readfile.open("LineUp.txt");
// Opens the text file InOrder
ofstream outfile;
outfile.open("InOrder.txt");
// Read name from file
while (readfile >> readName) {
// If first character of name != char(y),
// run loop
while (readName[0] != char(y)) {
y++;
lineNumber++;
// If first character of name = char(y),
// add name to lineNumber's position in array
if (readName[0] == char(y)) {
nameArray[lineNumber] = readName;
}
}
// Reset values of lineNumber and y
y = 65;
lineNumber = 0;
}
// Writes names in array to file
for (int x = 0; x <= 25; x++)
outfile << nameArray[x] << endl;
// Close files
readfile.close();
outfile.close();
// Print statement so you can see at least
// something happens
cout << "KIDS ORGANIZED. BEEP. BOOP. BEEP.\n";
cin.get();
return 0;
}
The output to the file made in the program that holds the ordered names:
Barb
John
Mary
Paul
Sam
Tom
Zev
(It contains many more empty lines than what stack overflow shows.)
The questions I have are as follows:
1: How can I get rid of the empty spaces in the array for when I want to write the names to the text file InOrder.txt?
2: The names Jackie and Bill are not being shows because the positions in the array are being overwritten by the other two names. How can I check if those positions are filled to add in these two names?
3: Is there anything in my program I can do to make it more efficient or more readable? Or just do better in general, I guess.
A big thank you to anyone willing to try to figure out how to solve these problems!

Answer 1

One problem is the length of your string array. You only reserve 26 elements. In your for loop
for (int x = 0; x <= 26; x++)
outfile << nameArray[x] << endl;
you try to access element 0 to 26 (that are 27 elements in total), that's more than you allocated. You have to change this loop to something like
for (int x = 0; x < 26; x++)
outfile << nameArray[x] << endl;
so it won't crash.
But the main problem in your program is the sorting system. As you already have noticed, as soon as two kids have a name with the same first letter, one name will be overwritten.
A better approach would be to use some of the standard libraries.
First i would not use a std::string array, but a std::vector. A vector is, simply said, a better and dynamic array with a lot more functions. If you want to know more about vectors, check here.
With a vector you can read every name first and sort it later:
std::vector<std::string> nameVector;
while(readfile >> readName) {
//add name to the end of the vector
nameVector.push_back(readName);
}
Now you can use std::sort() to sort the vector.
std::sort(nameVector.begin(), nameVector.end());
And last write everything to your output file:
for(int x = 0; x < nameVector.size(); ++x)
outfile << nameVector[x] << std::endl;

Answer 2

Firstly don't use the nameArray[26] in the for-loop as it is out of range.
Secondly by now surely you must have realized the issue. You logic reserve a place for name with each alhpabet and if there are two names starting with same alphabet it creates problem. Also the blank spaces are ther because of the places in the array not having any names starting with respective alphabet. for example. no name starts with A so a blank space will be in start of the file similary no name starts with C so a blank space would be there after the name Barb.
As per your logic the solution should be something like this:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
//Can be many names
string nameArray[100] = {};
int main() {
// Defined variables
int y = 65, lineNumber = 0;
string readName;
// Opens the text file LineUp
ifstream readfile;
readfile.open("LineUp.txt");
// Opens the text file InOrder
ofstream outfile;
outfile.open("InOrder.txt");
//Run while the names are not checked for all alphabets
while (y <= 90) {
// Read names from file till the end is reached
while (readfile >> readName) {
// If first character of name != char(y),
// run loop
if(readName[0] == char(y)) {
// If first character of name = char(y),
// add name to lineNumber's position in array
nameArray[lineNumber] = readName;
lineNumber++;
}
}
}
//Check File for next character
y++;
}
// Writes names in array to file
for (int x = 0; x < lineNumber; x++)
outfile << nameArray[x] << endl;
// Close files
readfile.close();
outfile.close();
// Print statement so you can see at least
// something happens
cout << "KIDS ORGANIZED. BEEP. BOOP. BEEP.\n";
cin.get();
return 0;
}
Note that this code works for only Upper-case letters and sorts only based on first alphabet.