How would I print numbers from a vector onto a file? - c++

Question

//Here is my code thus far
//HERE I SIMPLY TAKE IN A FILE FULL OF NUMBERS, INCLUDING DECIMAL NUMBERS
ifstream infile;
infile.open("Numbers.txt");
if (!infile) {
cout << "Unable to open the file" << endl;
return;
}
//CREATING VECTORS TO STORE THOSE NUMBERS IN
vector<int> iNumbers;
vector<double> dNumbers;
if (infile) {
int i;
double d;
while (infile >> i && infile >> d) {
iNumbers.push_back(i);
dNumbers.push_back(d);
}
infile.close();
}
/*
NOW ATTEMPTING TO PRINT OR PLACE THOSE NUMBERS INTO TWO DIFFERENT FILES PUTTING THE INTEGERS IN integer.txt AND PUTTING THE DOUBLES IN doubles.txt
*/
ofstream integerOut("integer.txt");
vector<int>::iterator ii;
for (ii = iNumbers.begin(); ii != iNumbers.end(); ++ii)
{
if (ii = int {
}
integerOut << *ii << endl;
cout << *ii << endl;
}
integerOut.close();
ofstream doubleOut("double.txt");
vector<double>::iterator dd;
for (dd = dNumbers.begin(); dd != dNumbers.end(); ++dd)
{
doubleOut << *dd << endl;
cout << *dd << endl;
}
doubleOut.close();
}
//MY CODE ONLY GIVES ME THE FIRST TWO NUMBERS FOR MY integer.txt FILE AND THE LAST DECIMALS FOR MY double.txt. WHAT AM I DOING WRONG?
Further explanation:
I have a file named Numbers.txt with numbers containing
1
5
9.4
3
4
6.3
5
2.2
I am taking the integers and trying to place them into the interger.txt file and I am taking the doubles and placing them into the double.txt file. But in my code I am receiving for integers
1
2
9
3
4
6
5
2
when I want to receive
1
5
3
4
5
only

Answer 1

You can use standard algorithm std::copy. For example
#include <iostream>
#include <fstream>
#include <iterator>
#include <algorithm>
//...
std::ofstream integerOut( "integer.txt" );
if ( integerOut )
{
std::copy( iNumbers.begin(), iNumbers.end(),
std::ostream_iterator<int>( integerOut, " " ) );
}
std::ofstream doubleOut( "double.txt" );
if ( doubleOut )
{
std::copy( dNumbers.begin(), dNumbers.end(),
std::ostream_iterator<double>( doubleOut, " " ) );
}
Or you can write a code where you will control the output yourself. For example
#include <iostream>
#include <fstream>
//...
std::ofstream integerOut( "integer.txt" );
for ( int x : iNumbers )
{
if ( !( integerOut << x << ' ' ) ) break;
}
std::ofstream doubleOut( "double.txt" );
for ( double x : dNumbers )
{
if ( !( doubleOut << x << ' ' ) ) break;
}
As for the input then as I have understood two integers are followed by one double in the file. So you need to read numbers accordingly.
int i1, i2;
double d;
bool valid = true;
while ( valid )
{
if ( valid = infile >> i1 ) iNumbers.push_back( i1 );
if ( valid && ( valid = infile >> i2 ) ) iNumbers.push_back( i2 );
if ( valid && ( valid = infile >> d ) ) dNumbers.push_back( d );
}
If you do not know whether the next number in the file is integer or double you can distiguish them by the presence of the period in the number. For example
std::string value;
while ( infile >> value )
{
if ( value.find( '.' ) != std::string::npos )
{
double d = std::stod( value );
dNumbers.push_back( d );
}
else
{
int i = std::stoi( value );
iNumbers.push_back( i );
}
}