小学生四则运算练习系统(C++编程)

#includestdio.h#includestdlib.h#includetime.hintmain(){inta,b,ans,res,t,i,c=0,N;intop;srand((unsigned)time(NULL));while(1){printf(\n---小学生四则运算练习系统---\n);printf(1.加法运算\n);printf(2.减法运算\n);printf(3.乘法运算\n);printf(4.除法运算\n);printf(5.退出练习\n);printf(请输入数字1-5:\n);scanf(%d,&op);switch(op){case1:printf(--请进行加法运算--\n);printf(--请输入题目个数--\n);scanf(%d,&N);for(i=1;i=N;i++){a=rand()%9+1;b=rand()%9+1;res=a+b;printf(%d+%d=,a,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}else{printf(wronganswer\n);printf(你还有一次机会\n);printf(%d+%d=,a,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}elseprintf(wronganswer\n);}}printf(***正确率为%.0f%%***\n,100.0*c/N);break;case2:printf(--请进行减法运算--\n);printf(--请输入题目个数--\n);scanf(%d,&N);for(i=1;i=N;i++){a=rand()%9+1;b=rand()%9+1;if(ab){t=a;a=b;b=t;}res=a-b;printf(%d-%d=,a,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}else{printf(wronganswer);printf(你还有一次机会\n);printf(%d-%d=,a,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}elseprintf(wronganswer\n);}}printf(***正确率为%.0f%%***\n,100.0*c/N);break;case3:printf(--请进行乘法运算--\n);printf(--请输入题目个数--\n);scanf(%d,&N);for(i=1;i=N;i++){a=rand()%9+1;b=rand()%9+1;res=a*b;printf(%d*%d=,a,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}else{printf(wronganswer);printf(你还有一次机会\n);printf(%d*%d=,a,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}elseprintf(wronganswer\n);}}printf(***正确率为%.0f%%***\n,100.0*c/N);break;case4:printf(--请进行除法运算--\n);printf(--请输入题目个数--\n);scanf(%d,&N);for(i=1;i=N;i++){a=rand()%9+1;b=rand()%9+1;res=a*b/b;printf(%d/%d=,a*b,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}else{printf(wronganswer);printf(你还有一次机会\n);printf(%d/%d=,a,b);scanf(%d,&ans);if(ans==res){printf(verygood!\n);c++;}elseprintf(wronganswer);}}printf(***正确率为%.0f%%***\n,100.0*c/N);break;case5:gotoEND;}}END:printf(---ByeBye---\n);return0;}