Sample Solutions to first Assignment. the C++/iostream way

 
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
 
const int MAX = 9000;
 
int year[MAX], month[MAX], day[MAX], time[MAX], temp[MAX], hum[MAX],
 wspd[MAX], wdir[MAX], pres[MAX];
int nrecords=0;
 
int StringToInt(string s)
{ int len=s.length();
 int value=0;
 char sign='+';
 for (int i=0; i<len; i+=1)
 { char c=s[i];
 if ((c=='+' || c=='-') && i==0)
 sign=c;
 else if (c<'0' || c>'9')
 break;
 else
  value=value*10+(c-'0'); }
 if (sign=='-') value=-value;
 return value; }
 
void main(void)
{ ifstream infile("weather.dat");
 if (infile.bad())
 { cout << "Could not read weather.dat" << endl;
 exit(1); }
 while (nrecords<MAX)
 { string yr, mn, dy, tim, tmp, hmd, ws, wd, pr;
 infile >> setw(5) >> yr >> setw(3) >> mn >> setw(3) >> dy 
 >> setw(5) >> tim >> setw(5) >> tmp >> setw(4) >> hmd 
 >> setw(4) >> ws >> setw(4) >> wd >> setw(4) >> pr;
 if (infile.eof()) break;
  year[nrecords]=StringToInt(yr);
 month[nrecords]=StringToInt(mn);
 day[nrecords]=StringToInt(dy);
 time[nrecords]=StringToInt(tim);
 temp[nrecords]=StringToInt(tmp);
 hum[nrecords]=StringToInt(hmd);
 wspd[nrecords]=StringToInt(ws);
 wdir[nrecords]=StringToInt(wd);
 pres[nrecords]=StringToInt(pr);
 nrecords+=1; }
 infile.close();
 cout << "1 = average temperature throughout year" << endl;
 cout << "2 = average temperature for a particular month" << endl;
 cout << "3 = average temperature for a particular time of day" << endl;
 cout << "4 = find windiest moment" << endl;
 cout << "5 = full report on a particular moment" << endl;
 cout << "6 = exit" << endl;
 while (1)
 { cout << "option: ";
 int option;
 cin >> option;
 if (option==1) avg_temp_all_year();
 else if (option==2) avg_temp_all_month();
 else if (option==3) avg_temp_for_time();
 else if (option==4) find_windiest();
 else if (option==5) report_on_moment();
 else if (option==6) break;
 else cout << "What are you talking about?" << endl; } }
 

// The following functions would of course be defined before main:
 
void avg_temp_all_year(void)
{ float total=0.0;
 for (int i=0; i<nrecords; i+=1)
 total+=temp[i];
 float avg=total/nrecords;
 cout << "Average temperature over all records is "
 << setprecision(3) << avg << " degrees Fahrenheit" << endl; }
 
void avg_temp_all_month(void)
{ cout << "which month (number 1-12): ";
 int mth;
 cin >> mth;
 float total=0.0, count=0.0;
 for (int i=0; i<nrecords; i+=1)
 if (month[i]==mth)
 { total+=temp[i];
 count+=1.0; }
 float avg=total/count;
 if (count==0.0)
 cout << "No records have month = " << mth << endl;
 else
 cout << "Average temperature in month " << mth << " is "
  << setprecision(3) << avg << " degrees Fahrenheit" << endl; }
 
void avg_temp_for_time(void)
{ cout << "what time (number 0000-2359): ";
 int tim;
 cin >> tim;
 float total=0.0, count=0.0;
 for (int i=0; i<nrecords; i+=1)
 if (time[i]==tim)
  { total+=temp[i];
 count+=1.0; }
 float avg=total/count;
 if (count==0.0)
 cout << "No records have time = " << tim << endl;
 else
 cout << "Average temperature at time " << setw(4) << setfill('0') << tim << " is "
 << setprecision(3) << avg << " degrees Fahrenheit" << endl; }
 
void find_windiest(void)
{ int windex=0, wmax=-999999;
 for (int i=0; i<nrecords; i+=1)
 if (wspd[i]>wmax)
 { wmax=wspd[i];
 windex=i; }
 cout << "Windiest moment is at " << setw(4) << setfill('0') << time[windex] << " on "
 << setw(4) << setfill('0') << year[windex] << "/" 
 << setw(2) << setfill('0') << month[windex] << "/" 
 << setw(2) << setfill('0') << day[windex]
 << ", speed was " << wmax << " mph" << endl; }
 
void report_on_moment(void)
{ int yr, mn, dy, tm;
 cout << "enter year month date time: ";
 cin >> yr >> mn >> dy >> tm;
 int found=0;
 for (int i=0; i<nrecords; i+=1)
 if (year[i]==yr && month[i]==mn && day[i]==dy && time[i]==tm)
 { found=1;
 cout << "on " << setw(4) << setfill('0') << year[i] << "/" 
 << setw(2) << setfill('0') << month[i] << "/" 
 << setw(2) << setfill('0') << day[i]
 << " at " << setw(4) << setfill('0') << time[i] << endl;
 cout << " temperature " << (temp[i]>=0 ? "+" : "-")
 << setw(3) << temp[i] << " degrees fahrenheit" << endl;
 cout << " humidity " << setw(3) << hum[i] << " %" << endl;
 cout << " wind speed " << setw(3) << wspd[i] << " mph" << endl;
 cout << " w direction " << setw(3) << wdir[i]
 << " degrees East from North" << endl; }
 if (found==0)
 cout << "no records for " << setw(4) << setfill('0') << yr << "/"
 << setw(2) << setfill('0') << mn << "/" 
 << setw(2) << setfill('0') << dy 
 << " at " << setw(4) << setfill('0') << tm << endl; }

So don't ever let anyone tell you the C++ way is easier.