是(x+y)表达式取整要不然就无法执行求余了，求余只能用两个整数进行。过程：x+y=77%2=11/4=0程序如下：#include #includevoid main(){float x=2.5,y=4.7; cout<}
2.5+4.7 == 7.2int(7.2) == 77%2 ==11/4==0
