Effective STL 43 Prefer algorithm calls to hand-written loops

ruihuank

于 2017-09-26 16:14:39 发布

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分类专栏： Effectiv STL 笔记文章标签： stl

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本文介绍了一个手写的循环函数，该函数用于填充一个双精度浮点数数组，并返回实际填充的数量。此外，还展示了如何将填充后的数据插入到双向队列中，并通过算法调用对数组中的每个元素进行变换操作。

hand-written loop

// this function takes a pointer to an array of at most arraySize
// doubles and writes data to it. It returns the number of doubles written.
size_t fillArray(double *pArray, size_t arraySize);

double data[maxNumDoubles];
size_t numDoubles = fillArray(data, maxNumDoubles);

deque<doble> d;
...
deque<double>::iterator insertLocation = d.begin();
for (size_t i = 0; i < numDoubles; ++i) {
    insertLocation = d.insert(insertLocation, data[i] + 41);
    ++ insertLocation;
}

algorithm call

transform(data, data + numDoubles, // copy all elements
          inserter(d, d.begin()),  // store the result in this range
          bind2nd(plus<double>(), 41)); // adding 41 to each.sessss