/* Code for exercise 5.12. |  | "C++ Solutions--Companion to The C++ Programming Language, Third Edition" | by David Vandevoorde; Addison-Wesley 1998; ISBN 0-201-30965-3. | | Permission to use, copy, modify, distribute and sell this software | and its documentation for any purpose is hereby granted without fee. | The author makes no representations about the suitability of this | software for any purpose.  It is provided "as is" without express or | implied warranty. `----------------------------------------------------------------------*/#include <assert.h>#include <stdio.h>#include <string>//using std::string;size_t count_charpair(string const &s, char a, char b) {   size_t result = 0;   string::const_iterator p = s.begin();   while(p!=s.end())      if (*p++==a)         if (p!=s.end() && *p==b)            ++result;   return result;}size_t count_charpair(char const *s, char a, char b) {   assert(s);   size_t result = 0;   while (*s)      if (*s++==a)         if (*s==b)            ++result;   return result;}int main() {   printf("Pairs ab in \"aabbaba\": %d\n",          count_charpair("aabbaba", 'a', 'b'));   printf("Pairs ab in string(\"aabbaba\"): %d\n",          count_charpair(string("aabbaba"), 'a', 'b'));}