Ex 3-4.cpp

// Exercise 3-4
// A little program to find the longest string(s).
// Note: the program does not check for strings that
// are entered more than once and will treat each
// instance separately. Improving the program such
// that each instance is treated separately shouldn't
// be too complicated, but since the minimum of the
// exercise has been met and since basically the same
// thing has been done in the previous exercise, we
// leave it at that.
// Furthermore, it has the same limitations as the
// program in the previous exercise, which are beyond
// the scope of the chapter.
// After I finished the exercise I realised that I was
// also asked to do the same for the shortest string.
// Since the solution is essentially the same I will
// forego on implementing it.
#include<iostream>
#include<string>
#include<vector>

using std::cout;		using std::cin;
using std::endl;		using std::vector;
using std::string;

int main(){
	// ask for the user's name
	cout << "Please enter your first name: " ;
	string name ;
	cin >> name ;
	cout << "Hello, " << name << "!" << endl ;
	
	// ask for and read a text or list of words
	cout << endl << "Please enter a text or a list of words, "
					"followed by end-of-file: " ;
	vector<string> entered_words ;
	string x ;
	// invariant: entered_words contains all the words entered so far
	while(cin >> x) {
		entered_words.push_back(x) ;
	}
	
	// check that the user has entered some words at all
	typedef vector<string>::size_type vec_ssz ;
	vec_ssz size = entered_words.size() ;
	if (size == 0) {
		cout << endl << "Aah, come on man. At least enter some words. Try again." ;
		return 1 ;
	}
	
	// create a variable to hold the length of the longest string
	size_t sz_longest_word ;
	
	// check whether each string is longer than the previously longest string
	// invariant: we have checked count strings so far
	for (vec_ssz count = 0; count != size; ++count) {
		size_t string_sz = entered_words[count].size() ;
		if (count == 0 || string_sz > sz_longest_word) {
		sz_longest_word = string_sz ;
		}
	}
	
	// write the output message
	cout << endl << "The largest string is " << sz_longest_word << " characters long."
		 << endl << "The following strings are " << sz_longest_word << " characters long:" ;
	
	// output the string or strings that is/are the longest
	// invariant: we have checked for count strings whether they match the criterium
	for(vec_ssz count = 0; count != size; ++count){
		size_t string_sz = entered_words[count].size() ;
		if (string_sz == sz_longest_word){
			cout << endl << entered_words[count] ;
		}
	}
	
	return 0 ;
}