C++ Productivity Hacks

Jeevan Chandra Joshi · 2021-06-12T12:20:23Z

1. Master Header File #include <bits/stdc++.h> Enter fullscreen mode Exit fullscreen mode 2. Faster I/O Operations ios :: sync_with_stdio ( 0 ); cin . tie ( 0 ); cout . tie ( 0 ); Enter fullscreen mode Exit fullscreen mode 3. Macros for Debugging #define deb(x) cout << #x << " : " << x << "\n" Enter fullscreen mode Exit fullscreen mode 4. Number of Digits int number = 12345 ; int digits = floor ( log10 ( number ) + 1 ); // 5 Enter fullscreen mode Exit fullscreen mode 5. Swap Two Numbers int a = 10 ; int b = 20 ; swap ( a , b ); // 20 10 Enter fullscreen mode Exit fullscreen mode 6. Number of Set Bits int n = 15 ; int setBit = __builtin_popcount ( n ); // 4 Enter fullscreen mode Exit fullscreen mode 7. Auto Keyword vector < int > v { 1 , 2 , 3 , 4 , 5 }; for ( auto x : v ) cout << x << " " ; // 1 2 3 4 5 Enter fullscreen mode Exit fullscreen mode 8. Inbuilt GCD Function int x = 12 ; int y = 16 ; int gcd = __gcd ( x , y ); // 4 Enter fullscreen mode Exit fullscreen mode 9. Lambda Function auto add = []( int x , int y ) { return x + y ; }; int sum = add ( 10 , 20 ); // 30 Enter fullscreen mode Exit fullscreen mode 10. Accumulate Function int sum = 10 ; int arr [] = { 20 , 30 , 40 }; sum = accumulate ( arr , arr + 3 , sum ); // 100 Enter fullscreen mode Exit fullscreen mode Tip: Use "\n" instead of endl;

#cpp #programming #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;

Top comments (2)

Sandor Dargo • Jun 13 '21

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.

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.
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 • Jul 3 '21

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!