通过const引用或值传递int，有什么区别吗? [英] Pass int by const reference or by value , any difference?

问题描述

当我将 int 和 double 之类的原语传递给函数时，最好通过const引用或值传递它们(假设我不更改变量的值)?

When I pass primitives like int and double to functions , is it better to pass them by const reference , or by value (assuming that I don't change the variable's value) ?

int getValueFromArray(int index)
{
    // return the value from the array
}


int getValueFromArray(const int& index)
{
    // return the value from the array
}

谢谢

推荐答案

对于基本类型，按值传递比按引用传递要好得多.编译器不仅没有间接的引用，而且还具有参考意义，它不得不担心潜在的混叠现象，这可能会破坏优化机会.

For primitive types, passing by value is much better than passing by reference. Not only is there no indirection, but with a reference, the compiler has to worry about potential aliasing, which can ruin optimization opportunities.

最后，按引用传递会使左值变得奇特的使用，这实际上可能导致链接器错误.如果内联电话，这个最后的问题就不会消失.

Finally, pass-by-reference causes lvalues to become odr-used, which can actually cause linker errors. And this final issue doesn't go away if the call gets inlined.

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