C++ Rand()各种实现

        参考链接：http://www.cplusplus.com/reference/cstdlib/rand/

使用实例：      

    v1 = rand() % 100;         // v1 in the range 0 to 99
    v2 = rand() % 100 + 1;     // v2 in the range 1 to 100
    v3 = rand() % 30 + 1985;   // v3 in the range 1985-2014