C++课程设计，小学四则运算器，能随机生成十以内的四则运算，并判断用户的正确性，统计正确率和平均做题时间，并输出相应的评语。-C++ Curriculum design, four primary computing device, can be randomly generated within the 10 four operations, and to judge the correctness of users, statistical accuracy rate and average