How to express sum in c++

Sums in C can be expressed in the following ways: a normal loop, std::accumulate, a ranged for loop, and std::reduce (C 20 and later). The choice depends on the amount of data, the need to operate on the elements, and the C version.

Representation of summation in C

In C, summation can be expressed in the following ways:

1. Ordinary loop

int sum = 0;
for (int i = 0; i < n; i++) {
    sum += arr[i];
}

2. std::accumulate

int sum = std::accumulate(std::begin(arr), std::end(arr), 0);

3. Range for loop

int sum = 0;
for (int num : arr) {
    sum += num;
}

4. std::reduce (C 20 and above)

int sum = std::reduce(std::begin(arr), std::end(arr), 0, std::plus<int>{});

Selection scheme

Which summation representation to choose depends on the specific situation. Generally speaking:

• Normal loop is suitable for small amounts of data or when some operations need to be performed on elements.
• std::accumulate Provides concise syntax and is suitable for large data volumes.
• Scope for loop Provides a short syntax that works in C 11 and later.
• std::reduce is the more general summation function available in C 20 and later.

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