C ++向量累加 [英] C++ vector accumulates

问题描述

我尝试使用向量的累加函数

I was trying to use the accumulate function for vectors

vector <double> A;
double B = 0;

A.reserve(100);
for(itr = 0; itr < 210; itr++)
{
    term1 = pow(r[itr], 12);
    term1 = 1/term1;
    term2 = pow(r[itr], 6);
    term2 = 2/term2;
    A.push_back(term1 - term2);
}
B = accumulate(A.begin(), A.end(), 0);

但是，我总是B = 0，而A有非零值

however, I always got B = 0, while A had nonzero values

推荐答案

std :: accumulate 是一个有点鬼祟的意思，结果的类型是类型的初始值，并且不是容器元素的类型！所以你的累加器产生 int s。

std::accumulate is a bit sneaky in the sense that the type of the result is the type of the initial value, and not the type of the container elements! So your accumulator produces ints.

/ code>：

accumulate(A.begin(), A.end(), 0.0);
//                             ^^^^^^^ literal of type double

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