How to decrement several variables in C++in a single line statement?

Question

Edit: I replaced the phrase 'in one line' by 'in a single line statement' since this is what I was looking for

Let's say we have the following variables at hand:

int a = 5;
int b = 9;

Is there a way to compress this ...

a--;
b--;

... into in a single line statement?? The question is not about decrementing multiple variables in a for loop, since this seems to be a common yet unrelated question.

You can always just put the two statements in the same line: `a--;b--;`. — Aziz, Jun 07 '20 at 08:03
@Diggi55: The reason I'm asking is because this may lead to less-readable code. It is always better to keep the code as clear as possible, even if it means few extra lines of code. — Aziz, Jun 07 '20 at 08:05
^^^ what the others say. When you get to line-by-line debugging, you will rapidly find out why skilled and experienced developers hate 'clever' code:) — Martin James, Jun 07 '20 at 08:31

score 4 · Accepted Answer · answered Jun 07 '20 at 08:04

4

You probably mean "in a single statement", not just "in a single line". Then you can use the comma-operator:

(a--,b--);

answered Jun 07 '20 at 08:04

Stephan Lechner

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Yes, I was looking for a single line statement ... I didn't know this word till now. Thanks :) – Diggi55 Jun 07 '20 at 08:08

QuentinUK · Answer 2 · 2020-06-07T11:19:36.030

3

// use a template
template<class ... Args>
void decr(Args& ... args){
    (... , --args);
}

decr(a,b,c);

// or, in C++20, auto
void decr(auto& ... args){
    (... , --args);
}

edited Jun 07 '20 at 11:19

answered Jun 07 '20 at 08:18

QuentinUK

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DasElias · Answer 3 · 2020-06-07T08:06:08.730

2

You could just write the statements in one single line, like this :

a--, b--;

(thanks to @Aziz for the improvement with the comma instead of the semicolon)

edited Jun 07 '20 at 08:06

answered Jun 07 '20 at 08:03

DasElias

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19

1

similarly, you can use a comma to separate them: `a--,b--;` – Aziz Jun 07 '20 at 08:04

score 1 · Answer 4 · answered Jun 07 '20 at 08:03

1

You can do like :

int a = 5;
int b = 4;
(a -= 1), (b -= 1);
std::cout << a << b;

Output: 43

answered Jun 07 '20 at 08:03

NixoN

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1
6
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score 1 · Answer 5 · answered Jun 07 '20 at 08:06

1

You can try something like :

#include <iostream>

using namespace std;

    main ()
    {
      int a = 5, b = 9;
      a--, b--;
      cout << a;
      cout << b;        
      return 0;
    }

Output: 48

answered Jun 07 '20 at 08:06

Mohit

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How to decrement several variables in C++in a single line statement?

5 Answers5