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C++ Cookbook
book

C++ Cookbook

by D. Ryan Stephens, Christopher Diggins, Jonathan Turkanis, Jeff Cogswell
November 2005
Beginner to intermediate content levelBeginner to intermediate
594 pages
16h 23m
English
O'Reilly Media, Inc.
Content preview from C++ Cookbook

4.17. Counting the Number of Characters, Words, and Lines in a Text File

Problem

You have to count the numbers of characters, words, and lines—or some other type of text element—in a text file.

Solution

Use an input stream to read the characters in, one at a time, and increment local statistics as you encounter characters, words, and line breaks. Example 4-26 contains the function countStuff, which does exactly that.

Example 4-26. Calculating statistics about a text file

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cctype>

using namespace std;

void countStuff(istream& in,
                int& chars,
                int& words,
                int& lines) {

   char cur = '\0';
   char last = '\0';
   chars = words = lines = 0;

   while (in.get(cur)) {
      if (cur == '\n' ||
          (cur == '\f' && last == '\r'))
         lines++;
      else
        chars++;
      if (!std::isalnum(cur) &&   // This is the end of a
          std::isalnum(last))     // word
         words++;
      last = cur;
   }
   if (chars > 0) {               // Adjust word and line
      if (std::isalnum(last))     // counts for special
         words++;                 // case
      lines++;
   }
}

int main(int argc, char** argv) {

   if (argc < 2)
      return(EXIT_FAILURE);

   ifstream in(argv[1]);

   if (!in)
      exit(EXIT_FAILURE);

   int c, w, l;

   countStuff(in, c, w, l);
1
   cout << "chars: " << c << '\n';
   cout << "words: " << w << '\n';
   cout << "lines: " << l << '\n';
}

Discussion

The algorithm here is straightforward. Characters are easy: increment the character count each time you call get on the input stream. Lines are only slightly more difficult, since the way a line ends depends on the operating ...

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Publisher Resources

ISBN: 0596007612Supplemental ContentErrata Page