C++ 从数组中找到平均值
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find average value from array
提问by user12074577
for some reason, I am getting a very weird negative nuber as my average for my program, here is my code:
出于某种原因，我得到了一个非常奇怪的负数作为我的程序的平均值，这是我的代码：
int sum, avg;
int size;
size = sizeof(array) / sizeof(array[0]);
sum = 0;
avg = 0;
for(int i = 0; i < size; i++){
sum += array[i];
}
avg = sum / size
My output is: -6.84941e+061
我的输出是：-6.84941e+061
回答by taocp
for(int i = 1; i < size; i++){
//^^should be 0
sum += array[i];
}
avg = sum / size; //pay attention to truncation when doing integer division
you should pay attention to truncation when divide integers. For example, 10/20 = 0in integer division.
meanwhile, you need to start from 0 when computing sum.
整数相除时要注意截断。例如，10/20 = 0在整数除法中。同时，计算 sum 时需要从 0 开始。
Your code should look like the following:
您的代码应如下所示：
//the average may not necessarily be integer
float avg = 0.0; //or double for higher precision
for (int i = 0; i < size; ++i)
{
sum += array[i];
}
avg = ((float)sum)/size; //or cast sum to double before division
