Difference between revisions of "Calculate the sum over a container"

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(Python)
(Common Lisp: no, list is a container)
Line 85: Line 85:
 
<highlightsyntax language="lisp">
 
<highlightsyntax language="lisp">
 
(apply #'+ list)
 
(apply #'+ list)
</highlightsyntax>
 
 
Even shorter:
 
 
<highlightsyntax language="lisp">
 
(+ list)
 
 
</highlightsyntax>
 
</highlightsyntax>
  

Revision as of 05:05, 5 August 2010

Related content:

This code demonstrates how to calculate the sum of a container (most often an array or similar structure).

See also

Implementations

Algol 68

The following function computes the sum of the elements of the array passed to it. The type of the array elements is called NUM, which can be defined as any suitable integer or real type.

MODE NUM = INT; # type of array element #

PROC sum = ([] NUM a) NUM :
    BEGIN
        NUM result := 0;
        FOR i FROM LWB a TO UPB a DO
            result +:= a[i]
        OD;
        result
    END

For instance, the call

sum((3, 4, 5, 6))

returns 18.

Assembly

INT_MAX = 2147483647.

sum proc
	mov ecx,DWORD PTR [esp]
	add esp,4
	xor eax,eax
	sum_loop1:
	add eax,DWORD PTR [esp]
	add esp,4
	cmp DWORD PTR [esp],2147483647
	jne sum_loop1
	mov DWORD PTR [esp],ecx
	ret
sum endp

C

Total of a series function. Terminate by using INT_MAX <highlightsyntax language="c"> //stdarg.h must be included for this type of function to be declared

  1. include <stdarg.h>

int total( int first, ... ) {

  int count = 0, sum = 0, i = first;
  va_list marker;
  va_start( marker, first );     /* Initialize variable arguments. */
  while( i != INT_MAX )
  {
     sum += i;                   //increases the sum
     i = va_arg( marker, int);   //Gets the next argument
  }
  va_end( marker );              // Resets the list
  return sum;

} </highlightsyntax>

C++

<highlightsyntax language="cpp">

  1. include<numeric>

sum = std::accumulate(coll.begin(),coll.end(),0); </highlightsyntax>

Common Lisp

<highlightsyntax language="lisp"> (reduce #'+ list) (reduce #'+ list :initial-value 0) ; improved version that also works with empty lists </highlightsyntax>

Another way:

<highlightsyntax language="lisp"> (apply #'+ list) </highlightsyntax>

Excel

=SUM([cells])

F#

<highlightsyntax language="fsharp"> Seq.sum container </highlightsyntax>

Haskell

<highlightsyntax language="haskell"> sum container </highlightsyntax>

Java

<highlightsyntax language="java122"> import java.util.*;

public class Total {

   public static int total(int... values) {
       int total = 0;
       for (int i : values) total += i;       
       return total;
   }
   public static void main(String[] args) {
       System.out.println("Total: %d: ", total(1,2,4,40));
       
   }

} </highlightsyntax>

OCaml

Summing is a special case of folding the addition operator starting with zero:

# let sum = List.fold_left ( + ) 0;;
val sum : int list -> int = <fun>

For example:

# sum [1; 2; 4; 40];;
- : int = 47

Perl

<HIGHLIGHTSYNTAX language="perl"> use List::Util qw(sum); sum @arr; sum 0, @arr; # improved version that also works with empty arrays </HIGHLIGHTSYNTAX>

Python

A function that sums the values in a sequence is built into python, its name is 'sum'. <highlightsyntax language="python"> assert sum([1,2,3]) == 6 </highlightsyntax>

Ruby

class Array
  def sum
    inject { |s, v| s += v }
  end
end

Or more concisely,

class Array
  def sum
    reduce(:+)
  end
end

Scheme

<highlightsyntax language="scheme"> (apply + list) </highlightsyntax>

Zsh

zsum() {
	local -a array
	array=(1 2 3 4 5)
	(( sum=${(j:+:)array} ))
	return sum
}