学步园

以下库完成的是直接获得等差数列求和的运行时常量，即从i开始加，i + (i + 1) + (i + 2) + ... + n的工具：

main函数用于测试：

#include <iostream><br /> using namespace std;<br /> template <int FROM, int TO><br /> struct IncreaseTo<br /> {<br /> enum { VALUE = FROM + IncreaseTo<FROM + 1, TO>::VALUE };<br /> };<br /> template <int TO><br /> struct IncreaseTo<TO, TO><br /> {<br /> enum { VALUE = TO };<br /> };<br /> int main()<br /> {<br /> cout << "The answer is: " << IncreaseTo<1, 10>::VALUE << endl;<br /> cout << "The answer is: " << IncreaseTo<0, 100>::VALUE << endl;<br /> cout << "The answer is: " << IncreaseTo<100, 100>::VALUE << endl;</p> <p> return 0;<br /> }<br />