Programming Forums > Application Development > C++

The Dark · Dec 8th, 2005, 2:34 AM

First off code tags are supposed to preserve indenting, to make it easier for people to read and hence to help you - in this case there doesn't seem to be any indenting - hopefully that it just because it has been swallowed by the forum, not because you don't indent.

OK, you are pretty close, here are some pointers, let me know if you need more details:
1. You don't need a vector for the letters, just using your occ vector is enough.
2. Give your occ vector an initial size of 26

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occ.resize(26);

3. Once you have found a character and lower cased it, you can find its fequency position in the vector by subtracting 'a' from it (e.g. 'b'-'a' gives 1). You can then use ++ to increment the count. Change

(Toggle Plain Text)

occ [ ch ] = occ [ ch ] + 1 ;

to

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occ[ch-'a']++;

4. Pass the occ vector to the frequence function, so that it can loop through and print it out

(Toggle Plain Text)

void frequency(vector<int> &occ);
...
  frequency(occ);
...
void frequency(vector<int> &occ)

The & there is to pass the vector by reference, rather than taking a copy of it.
5. Print out the frequencies using the same method you put them in (subtract 'a' from the letter

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    cout<<letter << occ[letter-'a'] << endl ;

You might want to put a space in between the letter and the count, and possibly not print out letters which have a zero count.

The Dark · Dec 8th, 2005, 2:39 AM

Also note that assert is a very ugly way of checking that your file opened - you would be much better off with something like:

(Toggle Plain Text)

  ifstream fin(infile.data());
  if (!fin.is_open())
  {
     cout << "Couldn't open input file " << infile.data() << endl;
     return 10;
  }
  ofstream fout(outfile.data());
  if (!fout.is_open())
  {
     cout << "Couldn't open output file " << outfile.data() << endl;
     return 10;
  }

The return value of 10 is so that the OS (or any other caller program) can tell that your program failed.

c_newbie · Dec 8th, 2005, 2:28 PM

[quote=The Dark]Give your occ vector an initial size of 26

(Toggle Plain Text)

occ.resize(26);

3. Once you have found a character and lower cased it, you can find its fequency position in the vector by subtracting 'a' from it (e.g. 'b'-'a' gives 1). You can then use ++ to increment the count. Change

(Toggle Plain Text)

occ [ ch ] = occ [ ch ] + 1 ;

to

(Toggle Plain Text)

occ[ch-'a']++;

4. Pass the occ vector to the frequence function, so that it can loop through and print it out

(Toggle Plain Text)

void frequency(vector<int> &occ);
...
  frequency(occ);
...
void frequency(vector<int> &occ)

The & there is to pass the vector by reference, rather than taking a copy of it.
5. Print out the frequencies using the same method you put them in (subtract 'a' from the letter

(Toggle Plain Text)

    cout<<letter << occ[letter-'a'] << endl ;

QUOTE]

thanks much .. this was alot of help ... your advice seemed so much more logical than what i had ...
but there are certain things i think i just need to remove completely from this program because i dont think they are necessary .. i just have too much going on in there and because of that i am still not gettiing any result .. i have worked on this so much i dont even know what i am doing again .. i probably just need to start from scratch maybe?

Klipt · Dec 8th, 2005, 2:42 PM

I think your problem was more an error in logic than an error in programming. Your initial source code looks like you're trying to store each letter instead of just the frequencies of each letter. The letters themselves are unneeded info.

The most important part of learning to program is learning to think like a computer scientist, not just to write like one

c_newbie · Dec 8th, 2005, 3:11 PM

yea ure right .. i think i had it figured all wrong from the beginning thats y i'm having so much trouble

i created a vector for the letters which i dont think was needed...
i'm just gonna have to start all over ...

DaWei · Dec 8th, 2005, 6:16 PM

You're at post #15. I posted pseudo-code in post #7 to help you think about the problem logically. Did you read and think about that? Is it just a waste of freakin' time to devote time to these questions? I took that pseudo-code and dumped it into a blank cpp file as comments, then fleshed it out. Here's your work done for you. Of course, it isn't the only way. It's compiled and run, but not exhaustively tested. No warranty.

(Toggle Plain Text)

#include <iostream>
#include <fstream>
#include <vector>
#include <string>

using namespace std;

// For error conditions
int utOh (string elProblemo)
{
    cerr << elProblemo << endl;
    return 1;
}

int main (int argc, char *argv [])
{
   // Generate a C++ string containing the desired alphabet in lower case.
   string theSet = "abcdefghijklmnopqrstuvwxyz";
   // Establish a vector of ints of the same length, elements initialized to zero.
   vector <int> theCount;
   for (int i = 0; i < theSet.size (); i++) theCount.push_back (0);
   // Open an input file
   ifstream inFile ("inputstuff.txt", ios::binary | ios::in);
   if (!inFile.good ()) return utOh ("File didn't open");
   string aLine;

   while (true)
   {
       // Read a line.
       getline (inFile, aLine, '\n');
       if (inFile.fail ()) break;
       // For each character in the line, convert it to lower case 
       // and use a string function to find its position in the 
       // alphabet string (observe that all characters may not be present 
       // -- pay attention to that search result).
       string::size_type thePos;
       for (int i = 0; i < aLine.size (); i++)
       {
           thePos = theSet.find (tolower (aLine [i]), 0);
           // Use that index to increment the corresponding element 
           // in the integer array.
           if (thePos != string::npos) theCount [thePos]++;
       }
   }
   for (int i = 0; i < theSet.size (); i++)
       cout << theSet [i] << " : " << theCount [i] << endl;
   cin.get ();
   return 0;
}

Quote:

Originally Posted by Output

a : 3
b : 1
c : 3
d : 4
e : 13
f : 3
g : 2
h : 7
i : 11
j : 1
k : 1
l : 5
m : 4
n : 7
o : 15
p : 1
q : 1
r : 5
s : 5
t : 12
u : 3
v : 1
w : 3
x : 1
y : 2
z : 1

Quote:

Originally Posted by The input file

This is line one.
This is line two.
Now is the time for all good men to come to the aid of their country.
The quick brown fox jumped over the lazy dog.

JDStud6 · Dec 9th, 2005, 9:26 AM

I'm bored, so I wrote it out in C# for some practice...using TheDark's way of subtracting the chars.

(Toggle Plain Text)

using System.IO;

class Occuring
{
	static void Main()
	{
        StreamReader reader = File.OpenText("test.txt");
        string input = reader.ReadLine().ToLower();
        int[] occur = new int[26];
        char[] alphabet = ("abcdefghijklmnopqrstuvwxyz").ToCharArray();
        char[] in1 = null;

        while (input != null)
        {
            in1 = input.ToLower().ToCharArray();

            for (int i = 0; i < input.Length; i++)
            {
                if (in1[i] != ' ' && in1[i] != '.')
                    occur[in1[i] - 'a'] += 1;
            }
            input = reader.ReadLine();
        }
        
        for (int i = 0; i < 26; i++)
        {
            System.Console.WriteLine(alphabet[i] + ":" + occur[i] + " ");
        }
	}
}

DaWei · Dec 9th, 2005, 9:38 AM

Looks essentially identical. The use of 'a' as a basis for deriving array offsets constrains the operation to a particular codeset.

Dec 8th, 2005, 2:34 AM	#11
The Dark Expert Programmer Join Date: Jun 2005 Posts: 884 Rep Power: 4	First off code tags are supposed to preserve indenting, to make it easier for people to read and hence to help you - in this case there doesn't seem to be any indenting - hopefully that it just because it has been swallowed by the forum, not because you don't indent. OK, you are pretty close, here are some pointers, let me know if you need more details: 1. You don't need a vector for the letters, just using your occ vector is enough. 2. Give your occ vector an initial size of 26 (Toggle Plain Text) occ.resize(26); occ.resize(26); 3. Once you have found a character and lower cased it, you can find its fequency position in the vector by subtracting 'a' from it (e.g. 'b'-'a' gives 1). You can then use ++ to increment the count. Change (Toggle Plain Text) occ [ ch ] = occ [ ch ] + 1 ; occ [ ch ] = occ [ ch ] + 1 ; to (Toggle Plain Text) occ[ch-'a']++; occ[ch-'a']++; 4. Pass the occ vector to the frequence function, so that it can loop through and print it out (Toggle Plain Text) void frequency(vector<int> &occ); ... frequency(occ); ... void frequency(vector<int> &occ) void frequency(vector<int> &occ); ... frequency(occ); ... void frequency(vector<int> &occ) The & there is to pass the vector by reference, rather than taking a copy of it. 5. Print out the frequencies using the same method you put them in (subtract 'a' from the letter (Toggle Plain Text) cout<<letter << occ[letter-'a'] << endl ; cout<<letter << occ[letter-'a'] << endl ; You might want to put a space in between the letter and the count, and possibly not print out letters which have a zero count.

Dec 8th, 2005, 2:39 AM	#12
The Dark Expert Programmer Join Date: Jun 2005 Posts: 884 Rep Power: 4	Also note that assert is a very ugly way of checking that your file opened - you would be much better off with something like: (Toggle Plain Text) ifstream fin(infile.data()); if (!fin.is_open()) { cout << "Couldn't open input file " << infile.data() << endl; return 10; } ofstream fout(outfile.data()); if (!fout.is_open()) { cout << "Couldn't open output file " << outfile.data() << endl; return 10; } ifstream fin(infile.data()); if (!fin.is_open()) { cout << "Couldn't open input file " << infile.data() << endl; return 10; } ofstream fout(outfile.data()); if (!fout.is_open()) { cout << "Couldn't open output file " << outfile.data() << endl; return 10; } The return value of 10 is so that the OS (or any other caller program) can tell that your program failed.

Dec 8th, 2005, 2:28 PM	#13
c_newbie Newbie Join Date: Dec 2005 Posts: 14 Rep Power: 0	[quote=The Dark]Give your occ vector an initial size of 26 (Toggle Plain Text) occ.resize(26); occ.resize(26); 3. Once you have found a character and lower cased it, you can find its fequency position in the vector by subtracting 'a' from it (e.g. 'b'-'a' gives 1). You can then use ++ to increment the count. Change (Toggle Plain Text) occ [ ch ] = occ [ ch ] + 1 ; occ [ ch ] = occ [ ch ] + 1 ; to (Toggle Plain Text) occ[ch-'a']++; occ[ch-'a']++; 4. Pass the occ vector to the frequence function, so that it can loop through and print it out (Toggle Plain Text) void frequency(vector<int> &occ); ... frequency(occ); ... void frequency(vector<int> &occ) void frequency(vector<int> &occ); ... frequency(occ); ... void frequency(vector<int> &occ) The & there is to pass the vector by reference, rather than taking a copy of it. 5. Print out the frequencies using the same method you put them in (subtract 'a' from the letter (Toggle Plain Text) cout<<letter << occ[letter-'a'] << endl ; cout<<letter << occ[letter-'a'] << endl ; QUOTE] thanks much .. this was alot of help ... your advice seemed so much more logical than what i had ... but there are certain things i think i just need to remove completely from this program because i dont think they are necessary .. i just have too much going on in there and because of that i am still not gettiing any result .. i have worked on this so much i dont even know what i am doing again .. i probably just need to start from scratch maybe?

Dec 9th, 2005, 9:26 AM	#17
JDStud6 Programmer Join Date: Jan 2005 Location: Charleston, SC www.wareonearth.com Posts: 57 Rep Power: 4	I'm bored, so I wrote it out in C# for some practice...using TheDark's way of subtracting the chars. (Toggle Plain Text) using System.IO; class Occuring { static void Main() { StreamReader reader = File.OpenText("test.txt"); string input = reader.ReadLine().ToLower(); int[] occur = new int[26]; char[] alphabet = ("abcdefghijklmnopqrstuvwxyz").ToCharArray(); char[] in1 = null; while (input != null) { in1 = input.ToLower().ToCharArray(); for (int i = 0; i < input.Length; i++) { if (in1[i] != ' ' && in1[i] != '.') occur[in1[i] - 'a'] += 1; } input = reader.ReadLine(); } for (int i = 0; i < 26; i++) { System.Console.WriteLine(alphabet[i] + ":" + occur[i] + " "); } } } using System.IO; class Occuring { static void Main() { StreamReader reader = File.OpenText("test.txt"); string input = reader.ReadLine().ToLower(); int[] occur = new int[26]; char[] alphabet = ("abcdefghijklmnopqrstuvwxyz").ToCharArray(); char[] in1 = null; while (input != null) { in1 = input.ToLower().ToCharArray(); for (int i = 0; i < input.Length; i++) { if (in1[i] != ' ' && in1[i] != '.') occur[in1[i] - 'a'] += 1; } input = reader.ReadLine(); } for (int i = 0; i < 26; i++) { System.Console.WriteLine(alphabet[i] + ":" + occur[i] + " "); } } }

Dec 9th, 2005, 9:38 AM	#18
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Looks essentially identical. The use of 'a' as a basis for deriving array offsets constrains the operation to a particular codeset. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Dec 8th, 2005, 2:42 PM	#14
Klipt Hobbyist Programmer Join Date: Dec 2005 Posts: 118 Rep Power: 0	I think your problem was more an error in logic than an error in programming. Your initial source code looks like you're trying to store each letter instead of just the frequencies of each letter. The letters themselves are unneeded info. The most important part of learning to program is learning to think like a computer scientist, not just to write like one

Dec 8th, 2005, 3:11 PM	#15
c_newbie Newbie Join Date: Dec 2005 Posts: 14 Rep Power: 0	yea ure right .. i think i had it figured all wrong from the beginning thats y i'm having so much trouble i created a vector for the letters which i dont think was needed... i'm just gonna have to start all over ...

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Programming Forums > Application Development > C++

Use Vectors To Calculate # Of Occurences