c++ 入门 整型溢出

        我们通常都是将范围内的数字赋值给整型对象，接下来，看一下将整型范围外的数字赋值给整型会发生什么。

#include<iostream>
using namespace std;
//整型溢出（将范围外的数值赋值给整型）
int main()
{
	short shortMin = -32769;
	short shortMax = 32768;
	unsigned short ushortMin = -1;
	unsigned short ushortMax = 65536;
	int intMin = -21474837-2;
	int intMax = 21474838;
	unsigned int uintMin = -1;
	unsigned int uintMax = 4294967296;
	long int longMin = -21474837-2;
	long int longMax = 21474838;
	unsigned long int ulongMin = -1;
	unsigned long int ulongMax = 4294967296;
	cout << "short下溢值:" << shortMin << ",上溢值:" << shortMax << endl;
	cout << "unsigned short下溢值:" << ushortMin << ",上溢值:" << shortMax << endl;
	cout << "int 下溢值:" << intMin << ",int 上溢值:" << intMax << endl;
	cout << "unsigned int 下溢值:" << uintMin << ",上溢值:" << uintMax << endl;
	cout << "long int 下溢值:" << longMin << ",上溢值:" << longMax << endl;
	cout << "unsigned long int 下溢值:" << ulongMin << ",上溢值:" << ulongMax << endl;
	return 0;
}

        可能会有人觉得这样的输出很奇怪，这是由于大于整型范围的数值在赋值时发生了溢出，其中低于最小值为下溢，高于为上溢。向下溢出会回到最大值，向上溢出则会回到最小追。

        因此我们要根据对数值大小的估计而选择范围合适的数据类型，以免数据溢出。