C++ Productivity Hacks

1. Master Header File

#include <bits/stdc++.h>

2. Faster I/O Operations

ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);

3. Macros for Debugging

#define deb(x) cout << #x << " : " << x << "\n"

4. Number of Digits

int number = 12345;
int digits = floor(log10(number) + 1); // 5

5. Swap Two Numbers

int a = 10;
int b = 20;
swap(a, b); // 20 10

6. Number of Set Bits

int n = 15;
int setBit = __builtin_popcount(n); // 4

7. Auto Keyword

vector<int> v{1, 2, 3, 4, 5};
for (auto x : v)
  cout << x << " "; // 1 2 3 4 5

8. Inbuilt GCD Function

int x = 12;
int y = 16;
int gcd = __gcd(x, y); // 4

9. Lambda Function

auto add = [](int x, int y) {
  return x + y;
};
int sum = add(10, 20); // 30

10. Accumulate Function

int sum = 10;
int arr[] = {20, 30, 40};
sum = accumulate(arr, arr + 3, sum); // 100

Tip: Use "\n" instead of endl;

Comments

[Sandor Dargo]

In my opinion it would be worth explaining why something is considered a productivity trick at what it does. Plus, prepend std:: in case it's needed, because your readers might not know that std::accumulate is part of the <numeric> header.

A few comments without wanting to be complete here.

1. In production environment never ever use <bits/stdc++.h>. It will blow the size of your software as it includes whatever, plus it's not portable between different compilers.

2. No. In 2021 you barely need macros. Start with this.

6.-8. In C++ there is no built-in __builtin_popcount nor __gcd. Some compilers might or might not provide them. But at least std::gcd is provided by the the standard library in <numeric> header.

+1) Productivity trick. Understand what you use and why you use it, that's the only thing that will boost your productivity in the long run.

[Amin Pial]

Please don't get me wrong. But let me be honest with you. This is not an "hack" rather the "worst possible software engineering practice". Yeah, "hacking" is an "anti-pattern" in SWE itself. Please avoid these type "magic numbers and library call". This is okay for some fancy competitive programming environment, not in Software Engineering.
Cheers!