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#include <iostream>
#include <fstream>
#include <iomanip>
#include <cctype> // for toupper function
using namespace std;
struct Country {
char name[16]; // country name
long pop; // population
double gdp; // gross domestic product
};
const char * file = "countries.dat";
// read and display contents of countries.txt;
// return number of records in file
int prntCtries(fstream & fil);
// update countries.txt; size is number of records
void updtCtries(fstream & fil, int size);
// add data to countries.txt
void addCtries(fstream & fil);
int menu(); // pulls up menu
int main()
{
fstream fin; // input file object
fstream fout; // output file object
int cnt = 0; // number of records in file
fout.open(file, ios::out | ios::binary);
fout.close();
int choice;
do{
choice = menu(); //choice for menu
switch(choice)
{
case 1:
cnt = prntCtries(fin);
break;
case 2:
cout << "This is the function I don't have! LOL " << endl;
break;
case 3:
addCtries(fin);
break;
case 4:
updtCtries(fin, cnt); // update file contents
break;
case 5:
cout << "Quitting program..." << endl << endl;
break;
default:
cout << "This is not a valid menu option!" << endl;
break;
}
}while(choice != 5);
if (cnt == -1) // problem encountered
exit(2);
cout << endl;
cnt = prntCtries(fin); // show file contents
if (cnt == -1) // problem encountered
exit(2);
fin.close(); // close file
return 0;
}//endmain
int prntCtries(fstream & fil) // end openFiles()
{
Country c;
int ndx = 0;
cout << fixed << showpoint << setprecision(1);
fil.open(file, ios::in | ios::binary);
if (fil.is_open()) {
fil.seekg(0); // position at beginning of file
cout << "Current contents of \"" << file << "\" file:\n";
cout << " Country \t Population (M) GDP ($M)\n";
while (fil.read(reinterpret_cast<char *>(&c), sizeof(c))) {
cout << ++ndx << ". " << setw(15) << c.name << setw(16) << c.pop << setw(16) << c.gdp << endl;
} // endwhile
if (fil.eof())
fil.clear(); // clear EOF flag
else { // possible error condition
cout << " *** Error reading " << file << endl;
return -1;
} // endif
} // endif-thenPart
else {
cout << " *** Open \"" << file << "\" for input failed ***\n";
return -1;
} // endif-elsePart
fil.close(); // close file
return ndx;
} // end prntCtries()
void updtCtries(fstream & fil, int size)
{
Country c;
int ndx = 0; // record number to change
streampos pos; // location of record to update
cout << fixed << showpoint << setprecision(1); // output formatting
fil.open(file, ios::out | ios::in | ios::binary);
cout << " Enter the record # to change: ";
cin >> ndx;
cin.get(); // get and ignore endline
--ndx; // we start indexes at zero
if (ndx < 0 || ndx >= size) {
cout << " *** Invalid record # - Adios!\n";
exit(3);
} // endif
pos = ndx * sizeof(Country);
fil.seekg(pos);
if (fil.fail()) {
cout << " *** seek failed ***\n";
return;
} // endif
fil.read(reinterpret_cast<char *>(&c), sizeof(c));
cout << "Country selected:\n";
cout << ndx+1 << ". " << setw(15) << c.name << setw(16) << c.pop << setw(16) << c.gdp << endl;
if (fil.eof())
fil.clear(); // clear EOF flag
cout << "Enter country name: ";
cin.get(c.name, 16);
//cout << " Country: " << c.name << endl;
cin.get(); // get and ignore endline
cout << " Enter population of " << c.name << ": ";
cin >> c.pop;
//cout << " Population: " << c.pop << endl;
cout << " Enter GDP of " << c.name << "(in USD): $";
cin >> c.gdp;
fil.seekg(pos); // set pointer to start of record
fil.write(reinterpret_cast<char *>(&c), sizeof(c));
if (fil.fail()) {
cout << " *** attempted write failed ***\n";
return;
} // endif
fil << flush; // force disk write
fil.close(); // close file
int k = prntCtries(fil); // print updated file
} // end updtCtries()
void addCtries(fstream & fil) // end openFiles()
{
Country c;
cout << fixed << showpoint << setprecision(1);
fil.open(file, ios::out | ios::app | ios::binary);
if (fil.is_open()) {
cout << "\n ... adding to \"" << file << "\" ...\n";
cout << "Enter country name (or or 'X' to quit): ";
cin.get(c.name, 16);
while (toupper(c.name[0]) != 'X') {
cout << " Country: " << c.name << endl;
cin.get(); // get and ignore endline
cout << " Enter population of " << c.name << ": ";
cin >> c.pop;
cout << " Population: " << c.pop << endl;
cout << " Enter GDP of " << c.name << "(in USD): $";
cin >> c.gdp;
fil.write(reinterpret_cast<char *>(&c), sizeof(c));
cin.get(); // get and ignore endline
cout << "\nEnter country name (or 'X' to quit) : ";
cin.get(c.name, 20);
} // endwhile
} // endif-thenPart
else {
cout << " *** Open \"" << file << "\" for input failed ***\n";
return;
} // endif-elsePart
fil.close(); // close file
} // end addCtries()
int menu()
{
int sel = 5; // menu selection
cout << "\n * * * M A I N M E N U * * *\n\n";
cout << "1. Print All Records " << endl;
cout << "2. Print One Specific Countries Info" << endl;
cout << "3. Add a Record" << endl;
cout << "4. Update a Record " << endl;
cout << "5. Quit " << endl;
cout << "\tEnter your choice (1..5): ";
cin >> sel;
while (sel < 1 || sel > 5) {
cout << "\tPlease enter 1 to 5: ";
cin >> sel;
} // endwhile
return sel;
}
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