parsing words out to pointer array

This is a discussion on parsing words out to pointer array within the C++ Programming forums, part of the General Programming Boards category; Hello, I hope someone can help me, I'm a little bit stuck. It's been a while since I did any ...

  1. #1
    Registered User
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    Oct 2001
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    23

    Unhappy parsing words out to pointer array

    Hello,

    I hope someone can help me, I'm a little bit stuck.
    It's been a while since I did any coding and this project is designed to get me back into it.

    Basically I want to take a string in from the user then break this string up into separate words, then store these words as an array of pointers to strings(or char arrays);

    Here's what I have, it compiles and runs but gives an unhandled exception...

    //code begin

    #include <iostream>
    #include <string.h>

    using namespace std;

    bool isalfa(char ch);

    void Split_String(char * Origin, char * Destination_array);

    int main()

    {

    char Array_Source[512];
    char * Array_of_Char_Poiners[50];

    cout<< "please enter a question string: \t";
    cin.getline(Array_Source, 512);

    Split_String(Array_Source, Array_of_Char_Poiners[50]);

    for(int a=0; a<=50; a++)

    cout << Array_of_Char_Poiners[a] << "\n";

    return 0;
    }





    void Split_String(char * Origin, char * Destination_array){

    char * p1;

    int i, j, k = 0;



    for(i=0; i<=512; i++){
    if(!isalfa(Origin[i]))
    i++;

    p1=new char[50];
    j=0;

    if(isalfa(Origin[i])){
    p1[j] = Origin[i];
    j++;
    }

    }
    }


    bool isalfa(char ch){

    if(ch>33 && ch<122)

    return true;

    else
    return false;
    }

    //code ends

  2. #2
    Cat without Hat CornedBee's Avatar
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    8,893

    Re: parsing words out to pointer array

    I tried to mend the code, but seriously, it is beyond repair.

    I suggest you do it again using std::vector and std::string. Here's a splitter function.
    Code:
    #include <vector>
    #include <string>
    using std::vector;
    using std::string;
    
    // this takes a string and splits it into an array of smaller strings
    // it's splitted every time split_at is encountered
    void split_string(const string &s, vector<string> & out, char split_at)
    {
    	// for searching the string
    	string::const_iterator stay, run;
    	// set stay to the start of the string
    	stay = s.begin();
    	// temporary
    	string t;
    	// loop run through the string, from front to back
    	for(run=stay; run != s.end(); ++run)
    	{
    		// if encountered split char...
    		if(*run == split_at)
    		{
    			// ...clear the temporary value...
    			t.erase();
    			// (speeds it up a little)
    			t.reserve(run-stay);
    			// ..., copy current substring to temporary...
    			t.append(stay, run);
    			// ...and add it to the array.
    			out.push_back(t);
    			// Finally, let the next substring begin directly after the splitting char.
    			stay = run+1;
    		}
    	}
    	// same as above for the last piece (from last split char to end of string)
    	t.erase();
    	t.reserve(run-stay);
    	t.append(stay, run);
    	out.push_back(t);
    }
    Alternativly, grab boost::string_tokenizer from www.boost.org
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  3. #3
    Cat without Hat CornedBee's Avatar
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    And a single tip: array indices are 0-based, so they go up to (size-1). The array iteration loop uses <, not <=.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  4. #4
    Registered User
    Join Date
    Oct 2001
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    23
    Thanks CornedBee,

    Is it really that bad?

    Thanks for the reply, I'll read through your solution now.

    M

  5. #5
    Cat without Hat CornedBee's Avatar
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    The Split_String function is a total chaos.
    And it allocates an awful lot of memory where at worst more than 99% is wasted.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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