通过数组末尾读取是否安全? [英] Is it safe to read past the end of an array?

问题描述

假设我有一个这样的构造函数:

Let's say I have a constructor like this:

MyColor(uint8 vec[]) {
r = vec[0];
g = vec[1];
b = vec[2];
a = vec[3];
}

但是我这样称呼它(3个元素而不是4个元素):

But I call it like this (3 elements instead of 4):

uint8 tmp[] = {1,2,3};
MyColor c(tmp);

但是现在vec[3]是不确定的...将此值分配给a是否安全?如果没有，没有很好的解决方法来检查是否设置了vec[3]?

But now vec[3] is undefined... is it safe to assign this value to a? If not, there's no nice workaround to check if vec[3] is set is there?

推荐答案

如果您不想使用矢量，请尝试此...

if you dont want to use vector try this...

MyColor(uint8 (&vec)[3])
{
   r = vec[0];
   g = vec[1];
   b = vec[2];
}

MyColor(uint8 (&vec)[4])
{
   //...
}

uint8 a1[] = {1,2,3};
MyColor c1(a1);
uint8 a2[] = {1,2,3,4};
MyColor c2(a2);
uint8 a3[] = {1,2,3,4,5};
MyColor c3(a3); // error

您不必显式地包括数组的大小，并且如果您尝试传递具有错误数目的元素的数组，则会生成编译错误，

you dont have to include the array's size explicitly and if you try to pass an array with wrong number of elements, compile error will be generated,

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