Task
Your task is to write a program, words, that reports information about the number of words read from its standard input. For example, if the file qbf.txt contains the text the quick brown fox jumps over the lazy dog then running the program with is input redirected to come from that file will report 9 words$ words < qbf.txt
Total: 9
Automatic TestingThis task is available for automatic testing using the name words. You can run the demo using demo words and you can test your work using try words <<filename>>.
Background
Use the following skeleton for the program:int main (int argc,
char
** argv
) {
enum {
total, unique
}
mode = total;
for (int c; (c = getopt(argc, argv, "tu")) != -1;) {
switch (c) {
case 't':
mode = total;
break;
case 'u':
mode = unique;
break;
}
}
argc -= optind;
argv += optind;
string word;
int count = 0;
while (cin >> word) {
count += 1;
}
switch (mode) {
case total:
cout << "Total: " << count << endl;
break;
case unique:
cout << "Unique: " << "** missing **" << endl;
break;
}
}
The getopt function (#include <unistd.h>) provides a standard way of handling option values in command-line arguments to programs. It analyses the command-line parameters argc and argv, looking for arguments that begin with '-'. It then examines all such arguments for specified option letters, returning individual letters on successive calls and adjusting the variable optind to indicate which arguments it has processed. Consult getopt documentation for details.
In this case, the option processing code is used to optionally modify a variable that determines what output the program should produce. By default, mode is set to total (indicating that it should display the total number of words read). The getopt code looks for the t and u options (which would be specified on the command line as -t or -u) and overwrites the mode variable accordingly. When there are no more options (indicated by getopt returning -1), argc and argv are adjusted to remove the option arguments that getopt has processed.
Level 1: Unique words
Extend the program so that if run with the u option (specified by the command-line argument-u), it displays the number of unique words. To count unique words, use the STL vector
class to keep track of which words you've already seen. When each word is read, check to see
if it's already in the vector; if it's not, insert it. The number of unique words will then be the
size of the vector.
Level 2: Your Own Vector
Modify your code so that it does not use the STL classes. You'll need to write your own classto keep track of the list of words. At this level, you can assume that there will be no more that
1000 unique words, so you can use a statically allocated array to store the items.
A minimal STL-compliant class (which will minimise the changes you need to make to your
main program) would have an interface like this:
template<
class T
>
class Vector {
public
:
typedef T
* iterator ;
Vector() {
<< code >>
}
iterator begin() {
<< code >>
}
iterator end() {
<< code >>
}
int size() {
<< code >>
}
iterator insert(iterator position,
const T& item) { << code >>
}
private
:
T items[1000];
int used;
};
Note that, unlike an ordinary class, a template class is defined entirely in a header file, so here won't be any Vector.cpp file. Also, you'll find it easier to define the template methods within the class scope because it avoids the need to specify the scope for each method individually. Note that the insert method returns an iterator (a pointer in the case of Vector) to the newly inserted item.
Level 3: Individual Word Counts
Extend the program so that if run with the i option it displays the counts of individual words in alphabetical order. For example the command words -i < qbf.txt should result in the output shown.Your program will need to store two pieces of information for each word. Define a struct called WordInfo that contains a string variable named text for the word's text, and an int variable named count for the number of times it's been seen. Then create a vector of WordInfo instead of a vector of string. When you add a new word, give it a count of 1. When you see a word that's already in the
vector, increment its count. The simplest way to display the result in alphabetic order is to keep the vector in sorted order as words are added, then simply iterate through the vector at the end. To keep the list sorted, iterate through the list until you find a word that's alphabetically after the new word or reach the end of the list, then insert at that position.
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