C++ 如何在C++中将数组中的所有数字相加？
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How to add all numbers in an array in C++?
提问by ShadowWesley77
Instead of typing
而不是打字
array[0] + array[1] //.....(and so on)
is there a way to add up all the numbers in an array? The language I'm using would be c++ I want to be able to do it with less typing than I would if I just typed it all out.
有没有办法将数组中的所有数字相加？我使用的语言将是 c++ 我希望能够以比我将它全部输入时更少的输入来完成它。
采纳答案by Kiersten Jay Raymond
Try this:
尝试这个：
int array[] = {3, 2, 1, 4};
int sum = 0;
for (int i = 0; i < 4; i++) {
sum = sum + array[i];
}
std::cout << sum << std::endl;
回答by dasblinkenlight
回答by Red Alert
Say you have an int array[N].
假设你有一个int array[N].
You can simply do:
你可以简单地做：
int sum = 0;
for(auto& num : array)
sum += num;
回答by jbo5112
If you use a valarray, there is a member function sum()for that.
如果您使用 a valarray，则有一个成员函数sum()。
#include <iostream> // std::cout
#include <valarray> // std::valarray
int main () {
std::valarray<int> myvalarray(4);
myvalarray[0] = 0;
myvalarray[1] = 10;
myvalarray[2] = 20;
myvalarray[3] = 30;
std::cout << "The sum is " << myvalarray.sum() << '\n';
return 0;
}
回答by FlyingPiMonster
The easiest way I can see to do this is to use a loop. The bonus is that you can use it on any integer array without rewriting much code at all. I use Java more often, so I hope there aren't too many syntax errors, but something like this should work:
我能看到的最简单的方法是使用循环。好处是您可以在任何整数数组上使用它，而无需重写太多代码。我更经常使用 Java，所以我希望没有太多的语法错误，但这样的事情应该可行：
int addArray(int[] array, int length){
int sum=0;
for(int count=0;count<length;count++){
sum+=array[count];
}
return sum;
}
回答by Mohammad Alaggan
In C++17, one could use fold expressions:
在 C++17 中，可以使用折叠表达式：
template<typename ...Ts>
int sum_impl(Ts&& ...a)
{
return (a + ...);
}
If sum_implhad a constant number of parameters, we could have called it like this:
如果sum_impl有固定数量的参数，我们可以这样称呼它：
std::apply(sum_impl, arr);
assuming arr is std::array<int, N>. But since it is variadic, it needs a little push with helpers:
假设 arr 是std::array<int, N>。但由于它是可变参数，因此需要使用助手进行一些推动：
using namespace std;
template <class Array, size_t... I>
int sum_impl(Array&& a, index_sequence<I...>)
{
return sum_impl(get<I>(forward<Array>(a))...);
}
template <class Array>
int sum(Array&& a)
{
return sum_impl(forward<Array>(a),
make_index_sequence<tuple_size_v<decay_t<Array>>>{});
}
Therefore, assuming these helpers are in place, the code will look something like this:
因此，假设这些助手已就位，代码将如下所示：
template<typename ...Ts>
int sum_impl(Ts&& ...a)
{
return (a + ...);
}
int main()
{
array<int, 10> arr{0,1,2,3,4,5,6,7,8,9};
cout << sum(arr) << "\n";
return 0;
}
回答by rashedcs
We may use user defined function.
我们可以使用用户定义的函数。
Code Snippet :
代码片段：
#include<bits/stdc++.h>
using namespace std;
int sum(int arr[], int n)
{
int sum=0;
for(int i=0; i<n; i++)
{
sum += arr[i];
}
return sum;
}
int main()
{
int arr[] = {1, 2, 3, 4, 5};
int n = distance(begin(arr), end(arr));
int total = sum(arr,n);
printf("%d", total);
return 0;
}
回答by Name_Guest
int Sum;
for(int& S: List) Sum += S;
