How can I make this shorter?( and more efficient)

[Alien000]

Trying to make this more efficient

if ( score < 60 )

    { grade = 'F'; }

if ( score >= 90 )

    { grade = 'A'; }

if ( score >= 80 && score < 90 )

    { grade = 'B'; }

if ( score >= 70 && score < 80 )

    { grade = 'C'; }

if ( score >= 60 && score < 70 )

    { grade = 'D'; }

[anup30]

#include <iostream>
using namespace std;

int main(){
	int score=75;
 	char grade;
 	if(score>=90) grade='A';
 	else if (score>=80) grade='B';
 	else if (score>=70) grade='C';
 	else if (score>=60) grade='D';
 	else grade='F';
 	
 	cout << "grade= " << grade << "\n";
return 0;
}

[lastchance]

#include <iostream>
using namespace std;

int main()
{
   int score;
   cout << "Input score [0-100]: ";   cin >> score;
   cout << "Grade = " << ( score >= 60 ? "DCBAA"[ ( score - 60 ) / 10 ] : 'F' ) << '\n';
}

[Duthomhas]

@anup32 That is the same as the OP’s code, just with less whitespace.
Sorry, my comment was not nice, nor correct. (See a few posts down for more.)


@Alien000
You should not worry too much about efficiency unless you can prove that it is an issue.

For shorter, you want to use a simple array lookup: see line 12:

#include <cmath>
#include <iostream>

int main()
{
  int score;
  {
    std::cout << "score? ";
    std::cin >> score;
  }
  
  std::cout << "FDCBA"[ std::max( 5, std::min( score / 10, 9 ) ) - 5 ] << "\n";
}

The score divided by 10 is one of 0, 1, 2, …, 9, 10, …
Next we use min and max to make sure it is clamped to the range 5..9.
Next we subtract 5 to index the beginning of our grades array ("FDCBA").

This is also “more efficient”, but unless you are processing several hundred thousand student grades, you won’t notice the difference.

Your current strategy is much more readable, and therefore a better answer.

Hope this helps.


[edit]
@lastchance
Timejumper!
You and I had the same brain wave.

[MikeStgt]

more efficient

Not more efficient in view of execution speed, but maybe for maintenance (for example a future revision may also contain grade E):

#include <iostream>
using namespace std;

int main()
{
	int score=75;
 	char grade('A');
 	
 	if (score < 90) grade='B';
 	if (score < 80) grade='C';
 	if (score < 70) grade='D';
 	if (score < 60) grade='F';  // grade E missing?
 	
 	cout << "grade= " << grade << "\n";
// return 0;
}

[anup30]

>

same as the OP’s code, just with less whitespace

not exactly same, op's code has 8 comparisons, while mine has 4.
and using 'else if' instead of 'if' for every grade, it becomes much more readable.

[MikeStgt]

much more readable

One should not underestimate this aspect. Possibly a teacher has to maintain it ;)

[Duthomhas]

@anup32
You are right. I will fix my comment above. Sorry. :^\

[Ganado]

Using max/min is sooo cliché... Let's remove those pesky if/elses, after all, things are always easier without decisions! :D

#include <cmath>
#include <iostream>

int main()
{
    int x;
    std::cout << "Input score: ";
    std::cin >> x;
    x = std::pow(99.99/(89.99-x),10.0)/(std::pow(99.9/(x+10),10.0)+std::pow(99.99/(89.99-x),10.0))*(x/10.0-5)+0.01; // note from dev who no longer works here: DO NOT CHANGE
    std::cout << "Grade = " << "FDCBAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"[x] << '\n';
}

The "AAAAAAAAAAAA" stands for what the program will do if you go out of bounds.

(I was trying to find a way to do this in the form of A sin(B x + C) + D, but couldn't find a valid solution...)

In serious: Both Mike's and Anup's code is equally "maintainable", IMO. But Duthomhas and lastchance break even on the code golfing award (and Duthomhas handles a greater input range).

[anup30]

among all these codes lastchance's program is the fastest. and the latest program is the slowest(by a big gap lol)