Thread: Is this programming exercise possible (don't answer with code, just is it possible?)

Okay, I asked this over in C++ forum, but I think it's just too much C for them there.
Maybe you guys can answer better.
In C++ Primer Plus, Chapter 5 question 8 it asks to:

Write a program that uses an array of char and a loop to read one word at a time
until the word ‘done’ is entered. The program should then report the number of
words entered (not counting done). A sample run could look like this:


Enter words (to stop, type the word done):
anteater birthday category dumpster
envy finagle geometry done for sure
You entered a total of 7 words.


You should include the cstring header file and use the strcmp() function to
make the comparison test.

I can get it, but it's cheating basically because I'm using && and that hasn't been covered yet. Neither has if/else.
So basically only do-while, while, and for statements have been covered.
So is the solution to this problem doable given the limited tools?

working code:

Code:

#include <iostream>
#include <cstring>


using namespace std;


int main() {
    int x,y = 0,done = 1;
    unsigned long z = 0;
    int Numwords = 0;
    int set = 0;
    char temp_input_line[80];
    char current_word [80] = "";
    
    do {
        cin.getline(temp_input_line,79);
        x=0;  // Set beginning array count to 0
        z = strlen(temp_input_line);
        while (x <= z ){        //While less than or equal to string lenght
            while (temp_input_line[x] != ' ' && x <= z){        //Check for Space or end of string
                current_word [y] = temp_input_line [x];
                x++;
                y++;
                set = done;                                //Set Flag that word started
            }
            x++;
                                                    //End check for space or string end
            Numwords += set;                            //Increase word count
            set = 0;  //Reset word count flag
            current_word [y + 1] = '\0';
            y = 0;
            done = done && (strcmp("done",current_word));             //If 'done' found, result is 0
        }                                       //End check less than string length
    }while (done);
    
    cout << "Number of words is : " << Numwords - 1 << endl;
    
    
    
    
    
    
    
    
    return 0;
}

Output:

one two three four
five six done eight nine ten
Number of words is : 6

Originally Posted by Salem

Of course it's possible.

You can start by actually using C instead of C++.

This is C except for the cout.

cout along with:

Code:

#include <iostream>
#include <cstring>
 
using namespace std;
// ...
cin.getline(temp_input_line,79);

You need to replace them with the appropriate C header files, and C I/O functions.

Originally Posted by rstanley

cout along with:

Code:

#include <iostream>
#include <cstring>
 
using namespace std;
// ...
cin.getline(temp_input_line,79);

You need to replace them with the appropriate C header files, and C I/O functions.

I'm going to deem this question not possible to answer with the tools supplied and put it in my errata sheet, and move on. None of these replies deal with the logic of answering the question.

Originally Posted by whiteflags

The simplest implementation I can think of is:

Code:

read a word
while (word is not "done") {
   increase the count
   read another word
}
print the count

Sorry if you felt we weren't helping. You only need to read one word at a time though, and you weren't doing that, so everything was more complicated than it really needed to be. Additionally, sorry if you think this is a handout.

This doesn't take into account multiple lines entered.
It is read a line, read the words in that line, then read another line IF 'done' is not found.

Originally Posted by Salem

Your house is built on sand.
I was fixing your foundations before helping you to fix the walls.

sorry, but it looked like you were nit picking.
So to understand what you are saying is this can't be done in C++, only C?
I don't think so.

No, he's not telling you it can't be done in C++ or C. He's telling you if you want to try to solve the problem in C then use C constructs not C++ constructs.

This problem can be easily solved in either C or C++. You just need to arrange the logic elements in the proper order.

Also the book you're trying to use is not a very good book if you want to learn C++, IMO the design of this book is not really the best way to learn C++. Also, IMO, relying only on "covered" material is not really the best way to learn any language, use what you know as well.

Jim

Originally Posted by Salem

If it can be done in any Turing-complete language, it can be done in ALL Turing-complete languages.

People write things like operating systems and web browsers in C and C++.
Makes me wonder why the OP should thing why this small problem might be impossible - impossible only to someone with limited skills perhaps.

Obviously you didn't read the post completely.
Let me repeat for you.
Using only do-while, while, and or for statements and not using && II or any if-else statements. ONLY using what has been learned up until this moment in the book which is summarized above; this question is not able to be programmed with the ABOVE stated tools.
Now, what the hell does Turing have to do with this post?
Maybe instead of speed reading maybe try comprehensive reading.

Originally Posted by FloridaJo

Using only do-while, while, and or for statements and not using && II or any if-else statements. ONLY using what has been learned up until this moment in the book which is summarized above;

One problem is that we don't know what has been taught up to that point in the book. I doubt only loops have been covered over the course of five chapters.

cin >> reads characters until whitespace is encountered. Maybe this will prove useful.
strcmp() returns a value that can be used to control a loop.

Does that inspire any ideas?

Originally Posted by Matticus

One problem is that we don't know what has been taught up to that point in the book. I doubt only loops have been covered over the course of five chapters.
...

This may give one an idea. Steve is fairly verbose which I like. He explains thing via many different angles.

Originally Posted by FloridaJo

This may give one an idea. Steve is fairly verbose which I like. He explains thing via many different angles.

So did the suggestions I offered give you any ideas for solving this problem?
The entire source for my solution is 20 lines (including declarations and whitespace).