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Iterators
This example demonstrates the usage of iterators in two ways:
- Usage1: It demonstrates how to use an iterator for manipulating
a container (vector). Use the iterator to find all the elements in the vector.
To insert the corresponding value into the vector after moving to a position
assignment, use the insert_iterator function.
Note: If insert_iterator is used several times to assign, then several elements are inserted into the underlying container.
- Usage2: An output iterator provides a mechanism for storing (but not necessarily accessing) a sequence of values. One example of output iterator is a tape. The user can write a value to the current location and advance to the next location, but cannot read values and cannot rewind. An ostream_iterator is an output iterator that performs formatted output of objects, of type T to a particular ostream. The function usage2 copies the elements of an array to the standard output, separated by hyphens (-) and the elements of the same array to a file TEST.DAT, one per line.
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MMP File for Iterators
TARGET OpenCPPiteratorsEx.exe TARGETTYPE exe UID 0 0xE28A7700 USERINCLUDE ..\inc SOURCEPATH . .\data START RESOURCE OpenCPPiteratorsEx_reg.rss #ifdef WINSCW TARGETPATH \private\10003a3f\apps #else TARGETPATH \private\10003a3f\import\apps #endif END //RESOURCE SOURCEPATH ..\src SOURCE OpenCPPiteratorsEx.cpp SYSTEMINCLUDE \epoc32\include SYSTEMINCLUDE \epoc32\include\stdapis SYSTEMINCLUDE \epoc32\include\stdapis\sys SYSTEMINCLUDE \epoc32\include\stdapis\stlport SYSTEMINCLUDE \epoc32\include\stdapis\stlport\stl STATICLIBRARY libcrt0.lib LIBRARY libstdcpp.lib LIBRARY libc.lib LIBRARY libpthread.lib LIBRARY euser.lib OPTION CW -wchar_t on MACRO _WCHAR_T_DECLARED
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Source Code for Iterators
Following code snippet demonstrates the usage of iterators to write applications using opencpp_plugin.
#include<iostream>
#include<vector>
#include<algorithm>
#include<fstream>
#include<iterator>
// This is a GCCE toolchain workaround needed when compiling with GCCE
// and using main() entry point
#ifdef __GCCE__
#include<staticlibinit_gcce.h>
#endif
using namespace std;
int usage1()
{
cout<<"Example to demonstrate insert Iterators\n";
vector<int>v;
vector<int>::iterator itr;
int i;
for(i=0; i<5; i++)
v.push_back(i);
cout << "Original array: ";
itr = v.begin();
while(itr != v.end())
cout << *itr++ << " ";
cout << endl;
itr = v.begin();
itr += 2; // point to element 2
// create insert_iterator to element 2
insert_iterator<vector<int>>i_itr(v, itr);
// insert rather than overwrite
*i_itr++ = 100;
*i_itr++ = 200;
cout << "Array after insertion: ";
itr = v.begin();
while(itr != v.end())
cout << *itr++ << " ";
cout<<"\nPress a character to continue!";
int c= getchar();
cout<<"\n\n\n";
return 0;
}
int usage2 ()
{
cout<<"Example to demonstrate os_stream iterator\n";
int ary[] = {2,5,7,2,8,9};
ofstream ofile("TEST.DAT");
// write to STDOUT
copy(ary,ary+6,ostream_iterator<int>(cout," - "));
// write into file "TEST.DAT"
copy(ary,ary+6,ostream_iterator<int>(ofile,"\n"));
ofile.close();
cout << endl;
ifstream ifile("TEST.DAT");
istream_iterator<int>start_file(ifile);
istream_iterator<int>end_file;
// read from file and write to STDOUT
copy(start_file,end_file,ostream_iterator(cout," * "));
ifile.close();
cout << endl;
cout<<"\nPress a character to exit!";
int c= getchar();
return 0;
}
int main()
{
usage1();
usage2();
return 0;
}