statfun.cpp

Think in C++ 第二版源码

//: C10:Statfun.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Static vars inside functions
#include "../require.h"
#include <iostream>
using namespace std;

char onechar(const char* string = 0) {
  static const char* s;
  if(string) {
    s = string;
    return *s;
  }
  else
    require(s, "un-initialized s");
  if(*s == '\0')
    return 0;
  return *s++;
}

char* a = "abcdefghijklmnopqrstuvwxyz";

int main() {
  // Onechar(); // require() fails
  onechar(a); // Initializes s to a
  char c;
  while((c = onechar()) != 0)
    cout << c << endl;
} ///:~