57 lines
1.7 KiB
C++
57 lines
1.7 KiB
C++
// newplace.cpp -- using placement new
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#include <iostream>
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#include <new> // for placement new
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const int BUF = 512;
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const int N = 5;
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char buffer[BUF]; // chunk of memory
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int main()
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{
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using namespace std;
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double *pd1, *pd2;
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int i;
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cout << "Calling new and placement new:\n";
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pd1 = new double[N]; // use heap
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pd2 = new (buffer) double[N]; // use buffer array
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for (i = 0; i < N; i++)
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pd2[i] = pd1[i] = 1000 + 20.0 * i;
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cout << "Memory addresses:\n" << " heap: " << pd1
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<< " static: " << (void *) buffer <<endl;
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cout << "Memory contents:\n";
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for (i = 0; i < N; i++)
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{
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cout << pd1[i] << " at " << &pd1[i] << "; ";
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cout << pd2[i] << " at " << &pd2[i] << endl;
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}
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cout << "\nCalling new and placement new a second time:\n";
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double *pd3, *pd4;
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pd3= new double[N]; // find new address
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pd4 = new (buffer) double[N]; // overwrite old data
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for (i = 0; i < N; i++)
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pd4[i] = pd3[i] = 1000 + 40.0 * i;
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cout << "Memory contents:\n";
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for (i = 0; i < N; i++)
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{
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cout << pd3[i] << " at " << &pd3[i] << "; ";
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cout << pd4[i] << " at " << &pd4[i] << endl;
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}
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cout << "\nCalling new and placement new a third time:\n";
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delete [] pd1;
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pd1= new double[N];
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pd2 = new (buffer + N * sizeof(double)) double[N];
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for (i = 0; i < N; i++)
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pd2[i] = pd1[i] = 1000 + 60.0 * i;
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cout << "Memory contents:\n";
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for (i = 0; i < N; i++)
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{
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cout << pd1[i] << " at " << &pd1[i] << "; ";
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cout << pd2[i] << " at " << &pd2[i] << endl;
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}
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delete [] pd1;
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delete [] pd3;
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// cin.get();
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return 0;
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}
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