C++常用的四种基本数值类型int unsigned float double 运行效率比较

最近在学习如何提高代码的运行效率，便索性把几种常用的基本数据类型的运算速率比较一下，代码和结果如下：

#include
#include
using namespace std;

int main()
{
	clock_t start, end;
	start = clock();
	for (int i = 0; i < 20000000; i++)
	{
		unsigned sum = 0;
		for (unsigned i = 0; i < 1000; i++)
		{
			sum += i;
		}
	}
	end = clock();
	cout << "无符号整型unsigned所用时间："<<(end - start) / CLK_TCK << endl;

	start = clock();
	for (int i = 0; i < 20000000; i++)
	{
		int sum = 0;
		for (int i = 0; i < 1000; i++)
		{
			sum += i;
		}
	}
	end = clock();
	cout << "基本整型int所用时间："<<(end - start) / CLK_TCK << endl;

	start = clock();
	for (int i = 0; i < 20000000; i++)
	{
		float sum = 0.0;
		for (float i = 0.0; i < 1000; i++)
		{
			sum += i;
		}
	}
	end = clock();
	cout << "单精度浮点型float所用时间：" << (end - start) / CLK_TCK << endl;

	start = clock();
	for (int i = 0; i < 20000000; i++)
	{
		double sum = 0.0;
		for (double i = 0.0; i < 1000; i++)
		{
			sum += i;
		}
	}
	end = clock();
	cout << "双精度浮点型double所用时间：" << (end - start) / CLK_TCK << endl;

	return 0;
}

运行结果如下：

结论：在比较中，无符号整型和基本整型的效率差不多，两种浮点型的效率差不多。所以以后能用整型表示的地方就尽可能不要使用浮点型，这效率可是高了一倍啊。