array problem

This is a discussion on array problem within the C++ Programming forums, part of the General Programming Boards category; hello, I am reading in a file and storing it into an array, and i am trying to find which ...

  1. #1
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    array problem

    hello,
    I am reading in a file and storing it into an array,
    and i am trying to find which letter appears most frequently in the array.
    how can this be accomplished?

    this is what i have so far. oh ya, and the file has spaces , but when i read contents of array there are no spaces.

    Code:
    #include <iostream>
    #include <fstream>
    #include <string>
    #include <iomanip>
    
    using namespace std;
    
    int main()
    {
    
    
    string line;  // also tried   char line[200];
    
    
    int count = 0;
    char reply;
    ifstream infile;
    string myfile;
    ifstream inputFile;
    
    
    
    inputFile.open ("encrypted.txt");
    
    if(!inputFile)
     {
        cerr << "Can't open input file " << myfile << endl;
    	cout << "Press enter to continue...";
        exit(1);
    }
    
    while (inputFile.peek() != EOF) {
    
    inputFile >> line;
    cout << line;
    }
    
        cin >> reply;
        return 0;
    }

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    You can't read strings with spaces in them with >>.

    If you want you can read a character at a time. To count, you can also use expressions inside the [brackets] of an array index -- so if you can just figure out how to get 'a' to be 0, and 'b' to be 1....

  3. #3
    Kernel hacker
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    If you want to read lines of text with spaces, then use istream::getline() http://www.cplusplus.com/reference/i...m/getline.html or string::getline() http://www.cplusplus.com/reference/string/getline.html

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  4. #4
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    ok i solved the space issue with getline, but not sure what you are talking about with
    to count most frequent letter in array? how can i do this?

  5. #5
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    still trying to read the file and find the most frequent letter.
    but somethings terribly wrong. I hope someone can help me see what i am doing so wrong.
    what i have so far:

    Code:
    #include <iostream>
    #include <fstream>
    #include <string>
    #include <iomanip>
    
    using namespace std;
    
    void charactercount ( char ch , int list[]);
    void copytext ( ifstream &intext, char &ch, int list[]);
    void writetotal (int list[]);
    
    
    
    int main()
    {
    
    int lettercount[26];
    char ch;
    
    char reply;
    ifstream infile;
    string myfile;
    ifstream inputFile;
    
    inputFile.open ("encrypted.txt");
    
    if(!inputFile)
     {
        cerr << "Can't open input file " << myfile << endl;
    	cout << "Press enter to continue...";
        exit(1);
    }
    
    
    inputFile.get(ch);
    
    while (inputFile)
    {
    	copytext(inputFile, ch, lettercount);
    	
    	inputFile.get(ch);
    }
    
    writetotal(lettercount);
    
    inputFile.close();
    
    cin >> reply;
        return 0;
    
    }
    
    void charactercount( char ch , int list[])
    {
    
    int index;
    
    ch = toupper(ch);
    
    index = static_cast<int>(ch) - static_cast<int>('A');
    
    if ( 0 <= index && index < 26)
    list[index]++;
    
    }
    
    void copytext ( ifstream &intext, char &ch, int list[])
    
    {
    
    	while ( ch != '\n')
    	{
    		charactercount(ch, list);
    		intext.get(ch);
    	}
    
    
    }
    
    void writetotal (int list[])
    {
    
    	int index;
    	for ( index = 0; index < 26; index++)
    	cout << static_cast<char>(index + static_cast<int>('A')) << " Count = " << list[index] << endl;
    }
    output:
    Code:
    A Count = -858992861
    B Count = -858993305
    C Count = -858993454
    D Count = -858992948
    E Count = -858992917
    F Count = -858992749
    G Count = -858993236
    H Count = -858993382
    I Count = -858993337
    J Count = -858993450
    K Count = -858993363
    L Count = -858993456
    M Count = -858992890
    N Count = -858993355
    O Count = -858993243
    P Count = -858993182
    Q Count = -858992487
    R Count = -858993265
    S Count = -858993303
    T Count = -858993052
    U Count = -858992940
    V Count = -858993425
    W Count = -858993438
    X Count = -858993169
    Y Count = -858993277
    Z Count = -858992891

  6. #6
    and the Hat of Guessing tabstop's Avatar
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    Most people count by starting at 0, rather than "p20487p-8asdfij" as you are.

  7. #7
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    What he meant is, you need to initialize your count array.

  8. #8
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    thank you cyberfish
    I think i know what to do now.
    fixed...
    Code:
    void initialize(int list[])
    {
    
    int j;
    
    for(j = 0; j < 26; j++)
    list[j] = 0;
    
    }
    Last edited by mrsirpoopsalot; 02-02-2009 at 12:24 AM.

  9. #9
    C++ Witch laserlight's Avatar
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    Instead of writing a function to initialise the array, actually initialise the array:
    Code:
    int lettercount[26] = {0};
    By the way, you should indent your code consistently. Also, in the future you might want to consider using a std::map<char, int> to map the letters to their counts.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  10. #10
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    laserlight,
    not sure about
    std::map<char, int>

    would this have been an easier way of doing what i did?
    I will also use google to find out what i can about map

  11. #11
    "I Win!" by U. Lose vart's Avatar
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    Quote Originally Posted by mrsirpoopsalot View Post
    laserlight,
    not sure about
    std::map<char, int>

    would this have been an easier way of doing what i did?
    I will also use google to find out what i can about map
    It will be C++-ier way to do the thing
    also it will solve the problem of out-of bounds access when your char is not one of the set 'A'-'Z'

    and another problem - if the codes of the chars above are not sorted
    To be or not to be == true

  12. #12
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    Code:
    void charactercount( char ch , int list[])
    {
    
    int index;
    
    ch = toupper(ch);
    
    index = static_cast<int>(ch) - static_cast<int>('A');
    
    if ( 0 <= index && index < 26)
    list[index]++;
    
    }
    There is no need for a cast in the red code - it's all done by implicit cast.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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