word count

// split function

vector<string> split(const string& s)
{
vector<string> ret;
typedef string::size_type string_size;
string_size i = 0;
// invariant: we have processed characters [original value of i, i)
while (i != s.size()) {
// ignore leading blanks
// invariant: characters in range [original i, current i) are all spaces
while (i != s.size() && isspace(s[i]))
++i;
// find end of next word
string_size j = i;
// invariant: none of the characters in range [original j, current j)is a space
while (j != s.size() && !isspace(s[j]))
j++;
// if we found some nonwhitespace characters
if (i != j) {
// copy from s starting at i and taking j - i chars
ret.push_back(s.substr(i, j - i));
i = j;
}
}
return ret;
}

The main should be something like :


#include <iostream>
#include <map>
using namespace std;
vector<string> split(const string& s);
int main()
{
string s;
map<string, int> counters; // store each word and an associated counter
// read the input, keeping track of each word and how often we see it
while (cin >> s)
++counters[s];
// write the words and associated counts
for (map<string, int>::const_iterator it = counters.begin(); it != counters.end(); ++it) {
cout << it->first << "\t" << it->second << endl;
}
return 0;
}