Help with a simple C++ program

Hey everyone, this is my first post in some time.. I need to create a simple C++ program that will count the number of words in an inputed sentence. I will admit that I am completely lost on how to do this..

I know posting questions to homework problems when looking for the exact answer or program as a reply is frowned upon, and please understand that is not what I am looking for. I simply wish for someone to point me in the right direction, or as to suggest what method, command, or function to use in my C++ program to count the number of words in an inputed string.

Thanks to all who who help! =)

Code:

#include <iostream>
#include <string.h>

char sentence;

int main()

{

std::cout << "Please enter a sentence and press Enter: ";
std::cin >> sentence;


return (0);
}

For starters:

Code:

#include <iostream>
//#include <string.h>     NO!
#include <string>

//char sentence;    Globals are evil

int main()
{
std::string input;

std::cout << "Please enter a sentence and press Enter: ";
//std::cin >> sentence;   This will stop with whitespace
std::getline(std::cin, input);   //reads a line of cin into 'input'

return (0);
}

Now to count. You can't count words, but, after all, what is a word (in a string)? It's a bunch of crap bookended by spaces. In general, a sentence with n spaces has n+1 words. So, what kind of algorithm could count whitespaces?

Code:

std::count(iterator,iterator,object_type);

So...

Code:

#include <iostream>
#include <string>
#include <algorithm> //for std::count

int main()
{
std::string input;

std::cout << "Please enter a sentence and press Enter: ";
std::getline(std::cin, input);

std::cout << ( std::count(input.begin(),input.end(),' ') + 1 ) << std::endl;       //Look from the beginning of the string to the end, counting the occurrences of the char ' '. 

return (0);
}

A few days ago I made a function that splits a string into a vector of words, also handles extra spaces nicely:

Code:

#include <iostream>
#include <string>
#include <vector>

std::vector<std::string> split(std::string text) {
  //hold the words in a vector of strings
  std::vector<std::string>args;
  if (text.length()==0) return args;
  //remove leading whitespace
  int firstnsp=text.find_first_not_of(" ");
  text=text.substr(firstnsp);
  //remove trailing whitespace
  int lastnsp=text.find_last_not_of(" ");
  text=text.substr(0,lastnsp+1);

  int i=0; //index to first character of current word
  int spi=0;//index of next space
  for(;;) {
    //find next space
    spi=0;
    for(int s=i;s<text.length();s++) {
      if (text[s]==' ') {spi=s;break;}
    }
    //break out of loop if no spaces were found
    if (spi==0) break;
    //add word to vector
    std::string newarg=text.substr(i,spi-i);
    if (newarg.length()>0) { //only add if the word has at least 1 character
      args.push_back(newarg);
    }
    //move up i to the character after the space
    i=spi+1;
  }
  //add final word to vector
  std::string lastarg=text.substr(i);
  if (lastarg.length()>0) {
    args.push_back(lastarg);
  }
}

int main() {
  std::string sentence="";
  std::cout << "Please enter a sentence and press Enter: ";
  getline (std::cin,sentence);
  std::vector<std::string> words=split(sentence);
  std::cout << "You entered " << words.size() << " words\n";
  return (0);
}

Cool. Using the stream's parsing capabilities is even more fun.

Code:

void f(const std::string & in, std::vector<std::string> & out)
{
   out.clear();
   std::istringstream s(in);
   std::string buf;
   while(s >> buf) out.push_back(buf);
}

PS: Your function doesn't seem to return a value. It has to. When it does, the entire vector will have to be copied. Yikes.

Originally Posted by CodeMonkey

For starters:

Code:

#include <iostream>
//#include <string.h>     NO!
#include <string>

//char sentence;    Globals are evil

int main()
{
std::string input;

std::cout << "Please enter a sentence and press Enter: ";
//std::cin >> sentence;   This will stop with whitespace
std::getline(std::cin, input);   //reads a line of cin into 'input'

return (0);
}

Now to count. You can't count words, but, after all, what is a word (in a string)? It's a bunch of crap bookended by spaces. In general, a sentence with n spaces has n+1 words. So, what kind of algorithm could count whitespaces?

Code:

std::count(iterator,iterator,object_type);

So...

Code:

#include <iostream>
#include <string>
#include <algorithm> //for std::count

int main()
{
std::string input;

std::cout << "Please enter a sentence and press Enter: ";
std::getline(std::cin, input);

std::cout << ( std::count(input.begin(),input.end(),' ') + 1 ) << std::endl;       //Look from the beginning of the string to the end, counting the occurrences of the char ' '. 

return (0);
}

Thank you so much, your post totally made me understand what I wasn't. Take care.