pointer.cpp

#include<bits/stdc++.h>
using namespace std;

void f(int* z) {
 *z = 25; 
}

void fref(int& z) {
 z = 25;
}

void sort(int *l, int* r) {
}

int z[10];

int* g() {
 int* t = (int*)malloc(10*sizeof(int));
 for (int i = 0; i < 10; i++) t[i] = i*i;
 return t;
}

/// O(v.size())
void fv(vector<int> v) {
}

/// O(1)
void fvref(vector<int> &v) {
}

/// O(1)
void fvpnt(vector<int> *v) {
}

void printArray(int* a, int n) {
 for (int i = 0; i < n; i++)
 cout << a[i] << ' ';
 cout << "\n----\n";
}

int main() {

 int x = 10;
 fref(x);
 cout << x << '\n';
 cout << "Value x: " << x << '\n';
 cout << "Address x: " << (&x) << '\n';
 int* p2x = &x;
 cout << "Address of pointed address: " << (p2x) << '\n';
 cout << "Address of p2x: " << (&p2x) << '\n';
 cout << "Value of p2x in ram: " << (*p2x) << '\n';
 x = 15;
 cout << "New value of x:" << (*p2x) << '\n'; // 15
 int** p2p2x = &p2x;
 cout << "Address of p2p2px in ram: " << (&p2p2x) << '\n';
 cout << "p2x: " << (*p2p2x) << '\n';
 cout << "*p2x == x: " << (**p2p2x) << '\n';
 *p2x = 20;
 cout << x << '\n';
 f(p2x);
 cout << x << '\n';

 int a[10];
 a[3] = 10;
 cout << (a) << '\n';
 /// a is pointer to first element of array
 cout << a[3] << '\n'; /// 10
 cout << (*(a+3)) << '\n'; /// 10
 sort(a, a+10);

 int* int_p = &x;
 cout << int_p << '\n';
 cout << (int_p+1) << '\n';

 bool b = false;
 bool* bool_p = &b;
 cout << bool_p << '\n';
 cout << (bool_p + 1) << '\n';


 char ch[5];
 ch[0] = '1';
 ch[1] = 'x';
 ch[2] = '-';
 cout << (ch) << '\n'; /// 1x-

 int* c = g();
 cout << (*c) << ' ' << (*(c+1)) << '\n';

 printArray(a, 10);


 int* pn = NULL;
 pn = &x;
}