//
// This is example code from Chapter 10.11.2 "Reading structured values" of
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//
#include "std_lib_facilities.h"
//------------------------------------------------------------------------------
const int not_a_reading = -7777; // less than absolute zero
const int not_a_month = -1;
//------------------------------------------------------------------------------
struct Day {
vector<double> hour;
Day(); // initialize hours to "not a reading"
};
//------------------------------------------------------------------------------
Day::Day() : hour(24)
{
for (int i = 0; i<hour.size(); ++i) hour[i]=not_a_reading;
}
//------------------------------------------------------------------------------
struct Month { // a month of temperature readings
int month; // [0:11] January is 0
vector<Day> day; // [1:31] one vector of readings per day
Month() // at most 31 days in a month (day[0] wasted)
:month(not_a_month), day(32) { }
};
//------------------------------------------------------------------------------
struct Year { // a year of temperature readings, organized by month
int year; // positive == A.D.
vector<Month> month; // [0:11] January is 0
Year() :month(12) { } // 12 months in a year
};
//------------------------------------------------------------------------------
struct Reading {
int day;
int hour;
double temperature;
};
//------------------------------------------------------------------------------
int month_to_int(string s);
bool is_valid(const Reading& r);
void end_of_loop(istream& ist, char term, const string& message);
//------------------------------------------------------------------------------
istream& operator>>(istream& is, Reading& r)
// read a temperature reading from is into r
// format: ( 3 4 9.7 )
// check format, but don't bother with data validity
{
char ch1;
if (is>>ch1 && ch1!='(') { // could it be a Reading?
is.unget();
is.clear(ios_base::failbit);
return is;
}
char ch2;
int d;
int h;
double t;
is >> d >> h >> t >> ch2;
if (!is || ch2!=')') error("bad reading"); // messed up reading
r.day = d;
r.hour = h;
r.temperature = t;
return is;
}
//------------------------------------------------------------------------------
istream& operator>>(istream& is, Month& m)
// read a month from is into m
// format: { month feb ... }
{
char ch = 0;
if (is >> ch && ch!='{') {
is.unget();
is.clear(ios_base::failbit); // we failed to read a Month
return is;
}
string month_marker;
string mm;
is >> month_marker >> mm;
if (!is || month_marker!="month") error("bad start of month");
m.month = month_to_int(mm);
Reading r;
int no_of_duplicate_readings = 0;
int no_invalid_readings = 0;
while (is >> r)
if (is_valid(r)) {
if (m.day[r.day].hour[r.hour] != not_a_reading)
++no_of_duplicate_readings;
m.day[r.day].hour[r.hour] = r.temperature;
}
else
++no_invalid_readings;
end_of_loop(is,'}',"bad end of month");
return is;
}
//------------------------------------------------------------------------------
const int implausible_min = -200;
const int implausible_max = 200;
bool is_valid(const Reading& r)
// a rough rest
{
if (r.day<1 || 31<r.day) return false;
if (r.hour<0 || 23<r.hour) return false;
if (r.temperature<implausible_min|| implausible_max<r.temperature)
return false;
return true;
}
//------------------------------------------------------------------------------
istream& operator>>(istream& is, Year& y)
// read a year from is into y
// format: { year 1972 ... }
{
char ch;
is >> ch;
if (ch!='{') {
is.unget();
is.clear(ios::failbit);
return is;
}
string year_marker;
int yy;
is >> year_marker >> yy;
if (!is || year_marker!="year") error("bad start of year");
y.year = yy;
while(true) {
Month m; // get a clean m each time around
if(!(is >> m)) break;
y.month[m.month] = m;
}
end_of_loop(is,'}',"bad end of year");
return is;
}
//------------------------------------------------------------------------------
void end_of_loop(istream& ist, char term, const string& message)
{
if (ist.fail()) { // use term as terminator and/or separator
ist.clear();
char ch;
if (ist>>ch && ch==term) return; // all is fine
error(message);
}
}
//------------------------------------------------------------------------------
vector<string> month_input_tbl; // month_input_tbl[0]=="jan"
void init_input_tbl(vector<string>& tbl)
// initialize vector of input representations
{
tbl.push_back("jan");
tbl.push_back("feb");
tbl.push_back("mar");
tbl.push_back("apr");
tbl.push_back("may");
tbl.push_back("jun");
tbl.push_back("jul");
tbl.push_back("aug");
tbl.push_back("sep");
tbl.push_back("oct");
tbl.push_back("nov");
tbl.push_back("dec");
}
//------------------------------------------------------------------------------
int month_to_int(string s)
// is s the name of a month? If so return its index [0:11] otherwise -1
{
for (int i=0; i<12; ++i) if (month_input_tbl[i]==s) return i;
return -1;
}
//------------------------------------------------------------------------------
vector<string> month_print_tbl; // month_print_tbl[0]=="January"
void init_print_tbl(vector<string>& tbl)
// initialize vector of output representations
{
tbl.push_back("January");
tbl.push_back("February");
tbl.push_back("March");
tbl.push_back("April");
tbl.push_back("May");
tbl.push_back("June");
tbl.push_back("July");
tbl.push_back("August");
tbl.push_back("September");
tbl.push_back("October");
tbl.push_back("November");
tbl.push_back("December");
}
//------------------------------------------------------------------------------
string int_to_month(int i)
// months [0:11]
{
if (i<0 || 12<=i) error("bad month index");
return month_print_tbl[i];
}
//------------------------------------------------------------------------------
void print_year(ostream& ost, const Year& y)
{
ost << y.year << ' ';
}
//------------------------------------------------------------------------------
int main()
try
{
// first initialize representation tables:
init_print_tbl(month_print_tbl);
init_input_tbl(month_input_tbl);
// open an input file:
cout << "Please enter input file name\n";
string name;
cin >> name;
ifstream ifs(name.c_str());
if (!ifs) error("can't open input file",name);
ifs.exceptions(ifs.exceptions()|ios_base::badbit); // throw for bad()
// open an output file:
cout << "Please enter output file name\n";
cin >> name;
ofstream ofs(name.c_str());
if (!ofs) error("can't open output file",name);
// read an arbitrary number of years:
vector<Year> ys;
while(true) {
Year y; // get a freshly initialized Year each time around
if (!(ifs>>y)) break;
ys.push_back(y);
}
cout << "read " << ys.size() << " years of readings\n";
for (int i = 0; i<ys.size(); ++i) print_year(ofs,ys[i]);
}
catch (exception& e) {
cerr << "error: " << e.what() << '\n';
return 1;
}
catch (...) {
cerr << "Oops: unknown exception!\n";
return 2;
}
//------------------------------------------------------------------------------