counting and printing the length of each word in a sentence

Question

#include <iostream>
#include <string>
#include <cctype>
size_t countwords(const char *);
using namespace std;

int main()
{
    char a[] =  "Four score and seven years ago";
    cout << countwords(a);

    return 0;
}

size_t countwords( const char *s )
{
    size_t count = 0;

    while ( *s )
    {
        while ( isspace( *s )) ++s;
        if ( *s ) ++count;
        while ( isalnum( *s )) ++s;
    }



    return ( count );
}

The only thing i'm missing and don't know how to perform is to print the length of each word in the sentence. I need my function to print the word and it's length side by side besides returning the word count. And also to print the average number of characters. so for example if the sentence was "four scores" I need:

Four 4
scores 5

average: 4.5

Answer 1

If you've got C++11, you can do this with <regex>. Note that some compilers aren't very compliant on this yet, but VC++12 (VS2013) seems to do it well, and GCC is coming along. Here's the entire program:

#include <iostream>
#include <string>
#include <functional>
#include <regex>
int main() {
    std::string input("Four score and seven years ago");
    std::regex exp(R"([\w]+)");
    int matches = 0, lengthSum = 0;
    std::for_each(
        std::sregex_token_iterator(input.begin(), input.end(), exp),
        std::sregex_token_iterator(),
        [&](std::ssub_match sm) {
            std::cout << sm << ": " << sm.str().size() << std::endl;
            matches++;
            lengthSum += sm.str().size();
        });
    std::cout << "Average: " << static_cast<float>(lengthSum) / matches << std::endl;
}

Answer 2

pseudo code in while()

if issapce() s++ print count count=0;
else count++ s++;

there is no difference with numbers and letters.

Answer 3

Consider this line...

while ( isalnum( *s )) ++s;

Before it starts, s points to the first character of a new word. After, it points to the first character after that new word. If we capture those two pointers...

const char *wordbegin = s;
while ( isalnum( *s )) ++s;
const char *wordend   = s;

You have pointers into your original string that identify the word. To get the length of the word, you can subtract the begin pointer from the end pointer. To output the word (using similar C-style code), you can loop through that range character by character.

To avoid that loop, you could temporarily change the pointed-to end character to a null, then back again after printing. [sorry - thinking of the old days before we used const].

You could also use one of the constructors of std::string to copy out and store that word, and then you could use the length method to read its length.

Answer 4

Without testing:

size_t countwords( const char *s )
{
    size_t count = 0;
    size_t total_length = 0;

    while ( *s )
    {
        while ( isspace( *s )) ++s;
        if ( *s )
        {
            ++count;

            size_t word_length = 0;
            while ( isalnum( *s ))
            {
                std::cout << *s;
                word_length++;
                ++s;
            }
            std::cout << '\t' << word_length << std::endl;
            total_length += word_length;
        }
    }

    std::cout << "average: " << ( count == 0 ? 0.0 : static_cast<double>( total_length ) / count )
              << std::endl; 

    return ( count );
}

Answer 5

#include <iostream>
#include <vector>
#include <sstream>


int main() {
    std::string line =  "Four score and seven years ago";
    std::vector<std::string> words;
    std::istringstream iss(line);
    std::string word;
    while( iss>>word ){
        words.push_back(word);
    }
    double sum = 0;
    for(int i=0; i<  words.size(); ++i){
        std::cout<<words[i]<<" "<<words[i].size()<<std::endl;
        sum += words[i].size();
    }

    std::cout<< "average:"<< sum/words.size()<<std::endl;
    return 0;
}

Answer 6

Note: count should be of type unsigned int, not size_t.

You can edit your code like this:

size_t countwords( const char *s )
{
    char *tmpWord = (char*) malloc(sieof(char)*strlen(s));
    int tmpLength = 0;
    while ( *s )
        {
            tmpLength = 0;
            while ( isspace( *s )) ++s;

            do{
                tmpWord[tmpLength++] = *s;
                ++s;
            }while(!isspace(*s));

            if ( *s ){ 
                ++count;
                printf("\n%s %d",tmpWord,--tmpLength);
            }
            while ( isalnum( *s )) ++s;
        }
free(tmpWord);
}