#include <iostream>
#include <algorithm>
using namespace std;
int main( ){
const int N = 10;
int static_arr[N];
for( int i = 0 ; i < N ; ++i )
cout << static_arr[i] << " ";
cout << endl;
fill( static_arr, static_arr + N, 0);
for( int i = 0 ; i < N ; ++i )
cout << static_arr[i] << " ";
cout << endl;
return 0;
}
|
| single element (1) | pair<iterator,bool> insert (const value_type& val); |
|---|---|
| with hint (2) | iterator insert (iterator position, const value_type& val); |
#include <set>
#include <iostream>
using namespace std;
int main( ){
set<int> s;
s.insert( 1 );
s.insert( 2 );
{
pair<set<int>::iterator,bool> ret = s.insert( 2 );
cout << *(ret.first) << " " << ret.second;
}
cout << endl;
{
pair<set<int>::iterator,bool> ret = s.insert( 3 );
cout << *(ret.first) << " " << ret.second;
}
}
|
set<int> s;
for( int i = 0 ; i < 10000000; ++i )
pair<set<int>::iterator,bool> ret = s.insert(i);
|
set<int> s;
for( int i = 0 ; i < 10000000; ++i )
set<int>::iterator ret = s.insert(s.end(), i);
|
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <algorithm>
using namespace std;
void shuffle( int *a, int n ){
int pickedLoc;
while( n != 0 ){
// choose a location "pickedLoc" to exchange
// the element on location n-1 with "pickedLoc"
pickedLoc = rand( ) % n--;
// swap
int temp = a[n];
a[n] = a[pickedLoc];
a[pickedLoc] = temp;
}
}
int find_redundant_linear( int *a, const int n ){
if( !a || n < 2 ) return -1;
bool *flag = new bool[n](); // flag[0] is unused
for( int i = 0 ; i < n ; ++i )
flag[a[i]] = !flag[a[i]];
for( int i = 0 ; i < n ; ++i )
if( !flag[a[i]] ){
delete [] flag;
return a[i];
}
}
int find_redundant_binarySearch( int *a, const int n ){
if( !a || n < 2 ) return -1;
int begin = 0;
int end = n-1;
int middle;
while( end != begin + 1 ){
middle = (begin + end) / 2;
if( a[middle] == middle )
end = middle;
else
begin = middle;
}
return a[begin];
}
int main( ){
// initialize an array with N numbers within [1, N-1]
// and only one number is redundant in this array
const int N = 101;
int arr[N];
int *p = arr;
int *q = arr + sizeof(arr)/sizeof(arr[0]);
int count = 1;
while( p != q )
*p++ = count++;
// create a redundant number
srand( time(NULL) );
arr[N-1] = rand( ) % (N-1) + 1;
cout << "The redundant number is " << arr[N-1] << endl;
// shuffle them
shuffle( arr, N );
// find redundant
int r = find_redundant_linear( arr, N );
cout << "The found redundant number is " << r << endl;
// sort the array
p = arr;
sort( p, q );
r = find_redundant_binarySearch( arr, N );
cout << "The found redundant number is " << r << endl;
}
|
char str[] = "ABCDE"; // sizeof(str): 6
char *p = str; // sizeof(p): 4
char q = *str; // sizeof(q): 1
int n = 10; // sizeof(n): 4
int *ptr = &n; // sizeof(ptr): 4 ; sizeof(*ptr): 4
|
int arr[] = {6, 7, 8, 9, 10};
int *ptr = arr;
*ptr++ += 123;
*++ptr += 123;
int *p = arr;
int *q = arr + sizeof(arr)/sizeof(*arr);
while( p != q )
cout << *p++ << " "; //129 7 131 9 10
|
*ptr++
*(ptr++)
*ptr++ += 123;
*++ptr += 123;
*ptr++ += 123;
*ptr++ = *ptr++ + 123;
int* arr1[8];
int (*arr2)[8];
int *(arr3[8]);
printf("size of arr1 = %d\n", sizeof(arr1)); // 32
printf("size of arr2 = %d\n", sizeof(arr2)); // 4
printf("size of arr3 = %d\n", sizeof(arr3)); // 32
|
union{
int num;
unsigned char n[4];
}q;
q.num = 10;
for( int i = 0 ; i< 4 ; i++)
printf("%x ", q.n[i]); // a 0 0 0
|
#include <iostream>
using namespace std;
class Animal{
public:
Animal() { cout << "Animal" << endl; }
~Animal() { cout << "~Animal" << endl; }
void move() { cout << "Animal move" << endl; }
virtual void eat() { cout << "Animal eat" << endl; }
};
class Dog: public Animal{
public:
Dog() { cout << "Dog" << endl; }
~Dog() { cout << "~Dog" << endl; }
void move() { cout << "Dog move" << endl; }
void eat() { cout << "Dog eat" << endl; }
};
int main( ){
{
Dog dog; // Animal
// Dog
Animal *pAnimal = &dog;
Dog *pDog = &dog;
pAnimal->eat(); // Dog eat
pAnimal->move(); // Animal move
pDog->eat(); // Dog eat
pDog->move(); // Dog move
} // ~Dog
// ~Animal
{
Dog *pDog = new Dog(); // Animal
// Dog
Animal *pAnimal = pDog;
pAnimal->eat(); // Dog eat
pAnimal->move(); // Animal move
pDog->eat(); // Dog eat
pDog->move(); // Dog move
delete pAnimal; // ~Animal
}
}
|
cout << sizeof(short int) << endl; // 2
cout << sizeof(unsigned short int) << endl; // 2
cout << sizeof(unsigned int) << endl; // 4
cout << sizeof(int) << endl; // 4
cout << sizeof(long int) << endl; // 4
cout << sizeof(signed char) << endl; // 1
cout << sizeof(unsigned char) << endl; // 1
cout << sizeof(float) << endl; // 4
cout << sizeof(double) << endl; // 8
cout << sizeof(long double) << endl; // 12
|
#include <iostream>
using namespace std;
class Add{
public:
Add( int x = 0 ) : val( x ) {}
int getVal() const {return val;}
void setVal( int x ) {val = x;}
Add& operator++();
private:
int val;
};
Add& Add::operator++(){
cout << "Increment " << val << endl;
++val;
return *this;
}
Add operator +(const Add& lhs, const Add& rhs)
{
cout << "Add " << lhs.getVal() << " and " << rhs.getVal() << "\n";
int added = lhs.getVal();
added = added + rhs.getVal();
return Add(added);
}
int main( ){
{
Add x(10), y(20);
++x = ++x + ++y;
cout << x.getVal() << endl;
}
cout << endl;
{
Add x(10), y(20);
Add z;
++z = ++x + ++y;
cout << z.getVal() << endl;
}
cout << endl;
{
Add x(10), y(20);
++x = ++y + ++x;
cout << x.getVal() << endl;
}
return 0;
}
|
Increment 10 Increment 20 Increment 11 Add 12 and 21 33 Increment 0 Increment 20 Increment 10 Add 11 and 21 32 Increment 10 Increment 11 Increment 20 Add 21 and 12 33
Increment 20 Increment 10 Add 11 and 21 Increment 11 32 Increment 20 Increment 10 Add 11 and 21 Increment 0 32 Increment 10 Increment 20 Add 21 and 11 Increment 11 32
#include <iostream>
using namespace std;
class Mat{
public:
Mat( const int *a, const int size );
~Mat();
void showElement() const;
void rotate( );
private:
int **m_image;
int m_size;
};
Mat::Mat( const int *a, const int size ) : m_image(NULL), m_size(size)
{
if( m_size <= 0 ) return;
m_image = new int*[m_size]( );
for( int i = 0 ; i < m_size ; i++ )
m_image[i] = new int[m_size]( );
// assign array value to member variable
for( int i = 0, p = 0 ; i < m_size ; i++ )
for( int j = 0 ; j < m_size ; j++ )
m_image[i][j] = a[p++];
}
Mat::~Mat(){
if(m_image){
for( int i = 0 ; i < m_size ; i++ )
delete [] m_image[i];
delete [] m_image;
}
}
void Mat::showElement() const{
for( int i = 0 ; i < m_size ; i++ ){
for ( int j = 0 ; j < m_size ; j++ )
cout << m_image[i][j] << " ";
cout << endl;
}
}
void Mat::rotate( ){
const int final_row = (m_size - 1) / 2;
const int final_col = (m_size % 2) ? (final_row - 1) : final_row;
const int final_index = m_size - 1;
// (i, j) -> (j, final_index-i) -> (final_index-i, final_index-j)
// -> (final_index-j, i) -> (i, j)
for( int i = 0 ; i <= final_row ; i++ ){
for( int j = 0 ; j <= final_col ; j++ )
{
int temp = m_image[final_index-j][i];
m_image[final_index-j][i] = m_image[final_index-i][final_index-j];
m_image[final_index-i][final_index-j] = m_image[j][final_index-i];
m_image[j][final_index-i] = m_image[i][j];
m_image[i][j] = temp;
}
}
}
int main( ){
const int SIZE = 4;
int image[SIZE * SIZE] = {1, 2, 3, 4,
5, 6, 7, 8,
9, 10,11,12,
13,14,15,16};
Mat mat( image, SIZE );
mat.showElement( );
mat.rotate( );
cout << endl;
mat.showElement( );
cout << endl;
const int SIZE2 = 5;
int image2[SIZE2 * SIZE2] = {1, 2, 3, 4, 5,
6, 7, 8, 9, 10,
11, 12, 13, 14, 15,
16, 17, 18, 19, 20,
21, 22, 23, 24, 25};
Mat mat2( image2, SIZE2 );
mat2.showElement( );
mat2.rotate( );
cout << endl;
mat2.showElement( );
return 0;
}
|
