Math.ceil(.95); // 1
Math.ceil(4); // 4
Math.ceil(7.004); // 8
Math.ceil(-0.95); // -0
Math.ceil(-4); // -4
Math.ceil(-7.004); // -7
It can be seen that Math.ceil() rounds up an integer of type int and is always the current value
Therefore, when we calculate int integers in Math.ceil, we should use a double type number
error:
int a,b
int c= (int) Math.ceil( a / b); //没有意义 Math.ceil计算的值永远等于a / b的值
correct:
int a,b
int c= (int) Math.ceil( a * 1.0 / b); //int整数运算向上转型变成double双精度运算 Math.ceil有意义