Mega Code Archive
Use vector as an array for user-defined object
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#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
class MyClass {
int p;
public:
MyClass() { p = 42; }
MyClass( int q ) { p = q; }
int getp() const { return p; }
void changeState( int pp ) { p = pp; }
};
bool operator<( const MyClass& x1, const MyClass& x2 ) {
return x1.getp() < x2.getp();
}
bool operator==( const MyClass& x1, const MyClass& x2 ) {
return x1.getp() == x2.getp();
}
void print( vector<MyClass> );
int main()
{
vector<MyClass> vec;
MyClass x1( 2 );
MyClass x2( 3 );
MyClass x3( 5 );
vec.push_back( x1 );
vec.push_back( x3 );
vec.push_back( x2 );
print( vec );
x2.changeState( 1000 );
print( vec);
//vector elements initialized by MyClass's no-arg constructor:
vector<MyClass> vec_2( 5 );
print( vec_2 );
vec_2.resize( 7 );
print( vec_2 );
//uninitialized increase in the vector capacity:
vec_2.reserve( 10 );
cout << vec_2.capacity() << endl;
print ( vec_2 );
cout << vec_2[ 8 ].getp() << endl;
vec_2[0] = MyClass(12);
vec_2[1] = MyClass(36);
vec_2[2] = MyClass(3);
vec_2[3] = MyClass(56);
vec_2[4] = MyClass(2);
sort( vec_2.begin(), vec_2.end() );
print( vec_2 );
vec_2.clear();
print( vec_2 );
cout << vec_2.capacity() << endl;
return 0;
}
void print( vector<MyClass> v ) {
cout << "\nvector size is: " << v.size() << endl;
vector<MyClass>::iterator p = v.begin();
while ( p != v.end() )
cout << (*p++).getp() << " ";
cout << endl << endl;
}
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