в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:31:13Z

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==Create istream_iterator for reading int values from cin==

<source lang="cpp">#include <iostream>
using std::cout;
using std::cin;
using std::endl;
#include <iterator>
int main()
{
cout << "Enter two integers: ";
std::istream_iterator< int > inputInt( cin );
int number1 = *inputInt;
++inputInt;
int number2 = *inputInt;
std::ostream_iterator< int > outputInt( cout );
cout << "The sum is: ";
*outputInt = number1 + number2;
cout << endl;
return 0;
}</source>
<pre class=codeResult>Enter two integers: 1 2
The sum is: 3</pre>

==Use istreambuf_iterator, ostreambuf_iterator, and replace_copy() to filter a file.==

<source lang="cpp">#include <iostream>
#include <fstream>
#include <iterator>
#include <algorithm>
using namespace std;
int main(int argc, char *argv[])
{
if(argc != 5) {
cout << "Usage: replace in out oldchar newchar\n";
return 1;
}
ifstream in(argv[1]);
ofstream out(argv[2]);
if(!in.is_open()) {
cout << "Cannot open input file.\n";
return 1;
}
if(!out.is_open()) {
cout << "Cannot open output file.\n";
return 1;
}
// Create stream iterators.
istreambuf_iterator<char> in_itr(in);
ostreambuf_iterator<char> out_itr(out);
// Copy the file, replacing characters in the process.
replace_copy(in_itr, istreambuf_iterator<char>(),out_itr, *argv[3], *argv[4]);
in.close();
out.close();
return 0;
}</source>

==Use istream_iterator==

<source lang="cpp">#include <iostream>
#include <iterator>
using namespace std;
int main()
{
istream_iterator<char> in_it(cin);
do {
cout << *in_it++;
} while (*in_it != ".");
return 0;
}</source>
<pre class=codeResult>a
a
aa
aa
aa
aa
aaaaaaa^CTerminate batch job (Y/N)? n</pre>

==Use istream_iterator and ostream_iterator to read from cin and write to cout.==

<source lang="cpp">#include <iostream>
#include <iterator>
#include <string>
#include <vector>
using namespace std;
int main()
{
unsigned i;
double d;
string str;
vector<int> vi;
vector<double> vd;
vector<string> vs;
cout << "Enter some integers, enter 0 to stop.\n";
istream_iterator<int> int_itr(cin);
do {
i = *int_itr;
if(i != 0) {
vi.push_back(i);
++int_itr;
}
} while (i != 0);
cout << "Enter some doubles, enter 0 to stop.\n";
istream_iterator<double> double_itr(cin);
do {
d = *double_itr;
if(d != 0.0) {
vd.push_back(d);
++double_itr;
}
} while (d != 0.0);
cout << "Enter some strings, enter "quit" to stop.\n";
istream_iterator<string> string_itr(cin);
do {
str = *string_itr;
if(str != "quit") {
vs.push_back(str);
++string_itr;
}
} while (str != "quit");
cout << endl;
cout << "Here is what you entered:\n";
for(i=0; i < vi.size(); i++) cout << vi[i] << " ";
cout << endl;
for(i=0; i < vd.size(); i++) cout << vd[i] << " ";
cout << endl;
for(i=0; i < vs.size(); i++) cout << vs[i] << " ";

// Now, use ostream_iterator to write to cout.
// Create an output iterator for string.
ostream_iterator<string> out_string_itr(cout);
*out_string_itr = "\n";
*out_string_itr = string("\nThis is a string\n");
*out_string_itr = "This is too.\n";
// Create an output iterator for int.
ostream_iterator<int> out_int_itr(cout);
*out_int_itr = 10;
*out_string_itr = " ";
*out_int_itr = 15;
*out_string_itr = " ";
*out_int_itr = 20;
*out_string_itr = "\n";
// Create an output iterator for bool.
ostream_iterator<bool> out_bool_itr(cout);
*out_bool_itr = true;
*out_string_itr = " ";
*out_bool_itr = false;
return 0;
}</source>

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