Exercise 5.10 (ACCELERATED C++)

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  1. #1
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    Exercise 5.10 (ACCELERATED C++)

    ....
    Last edited by pantera; 05-10-2010 at 07:33 AM.

  2. #2
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    Hi, I don't know how to stop the message "The longest palidrome is" from appearing if the user doesn't enter anything (just entering EOF). Where should I put that phrase? I'm not sure enough about the meaning of try-catch stuff. Thanks a lot...

    Code:
    /*
    	Write a program to (1) find all the palindromes in a dictionary and (2) find the longest palindrome
    */
    #include <iostream>
    #include <string>
    #include <vector>
    #include <stdexcept>
    #include <algorithm>
    using namespace std;
    
    vector<string> read_words(string&);
    bool found(const string&);
    
    int main()
    {
    	cout << "Enter some words: " << endl;
    	string s;
    	try {
    		vector<string> myvec = read_words(s);
    		vector<string>::iterator it = myvec.begin();
    		while (it != myvec.end()) {
    			if (found(*it)) {
    				cout << *it << " ";
    				++it;
    			}
    			else {
    				it = myvec.erase(it);
    			}
    		}
    		cout << endl;
    		cout << "The longest palidrome is ";
    		string::size_type maxlen = 0;
    		string longest;
    		for (int i = 0; i != myvec.size(); ++i) {
    			if (myvec[i].size() > maxlen) {
    				maxlen = max(maxlen, myvec[i].size());
    				longest = myvec[i];
    			}
    		}
    		cout << longest << endl;
    
    	} catch (domain_error e) {
    		e.what();
    	}
    
    	return 0;
    }
    
    vector<string> read_words(string& s)
    {
    	vector<string> v;
    	while (cin >> s)
    		v.push_back(s);
    
    	typedef vector<string>::size_type vec_sz;
    	vec_sz size = v.size();
    	if (size == 0)
    		throw domain_error("Empty vector");
    
    	return v;
    
    }
    
    bool found(const string& s)
    {
    	bool found = true;
    	for (string::const_iterator i = s.begin(), j = s.end() - 1; i < j; ++i, --j) {
    		if (*i != *j)
    			found = false;
    	}
    	return found;
    }

  3. #3
    and the Hat of Guessing tabstop's Avatar
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    If the user enters no text, but an immediate EOF, the line "The longest palindrome is: " is not printed. If you change your catch to be
    Code:
    cout << e.what();
    then you'll see "Empty vector" printed instead.

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