C++ Cheat Sheet

#include <iostream>:
using namespace std;

int main(int argc, const char * argv[]) {
    cout << "Hello World!";
}

// with a line break:
cout << "Hello World!\n";
// generates the same result:
cout << "Hello World!" << endl;

cout << "First " << "Second " << "Third";
cout << "First" << endl << "Second";
// printing the return-value of a function:
int add(int x) {
    return x+x;
}

int main(int argc, const char * argv[]) {
    cout << add(2); // 4
}

std::cout << "Enter string:" << endl;
std::string s;
std::getline(std::cin, s);
std::cout << "the string was: " << s << std::endl;

int add(int x) {
    return x;
}

int add(int x, int y) {
    return x+y;
}

// this won't work:
int add(int x, y) {
    return x+y;
}

int add(int x) {
    cout << "int function";
    return x+x;
}

double add(double x) {
    cout << "double function";
    return x+x;
}

int main(int argc, const char * argv[]) {
    cout << add(2.5); // double function
    cout << add(2);   // int function
}

int add (int a, int b) {
  return a + b; 
}

int useFn(int a, int b, function<int(int, int)> fn) {
  return fn(a, b); 
}

int main() {
  cout << useFn(2, 3, &add) << endl; 
}

void PrintValue(int value) {
  cout << "Value: " << value << endl;
}
    
void ForEach(
  const vector<int> &values, void (*func)(int)
) {
  for (int value : values) {
    func(value);
  }
}
    
int main() {
  vector<int> values = {1, 2, 3, 4, 5};
  ForEach(values, PrintValue);
  return 0;
}

auto lambda = []() { cout << "Hi" << endl; };

lambda(); 

int a = 5; 

auto lambda = [a]() { cout << "Hi" << endl; };

lambda();

int numbers[] = {1, 2, 3, 4, 5};

// alternatively: 
int numbers[2]; 
numbers[0] = 1; 
numbers[1] = 2;

int numberes[5]; 

for (int i = 0; i < 5; i++) 
  numbers[i] = 2; 

int numbers[5];
int* ptr = numbers;
      
numbers[2] = 5;
// value change: 
*(ptr + 2) = 6;
    
// printing 6   
cout << numbers[2] << endl;

int* anotherArray = new int[5]; 
delete[] anotherArray; 

int a[5]; 
int count = sizeof(a) / sizeof(int); 

int *returnArr() {
  int coordinates[2] = {1, 2};
  return coordinates;
}
    
int main()  {
  int x = returnArr()[0];
}

void multiply(int nums[3]) {
  for (int i = 0; i < 3; i++) {
    cout << nums[i] * 2 << endl;
  }
}
    
int main() {
  int nums[3] = {1, 2, 3};
  multiply(nums);
  return 0;
}

int number = 420; 
int numberPointer = *number;