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int a = 3; int b = 2; System.out.println(a + b); System.out.println(a - b); System.out.println(a * b); //除法会下取整 System.out.println(a / b); //进行乘法/取模运算时右操作数不能为0 报 Exception in thread "main" java.lang.ArithmeticException: / by zero 错误 System.out.println(a % b); double c = a*1.0 / b; //将a进行转换/提升为浮点数,之后在参与运算,则b也会进行相应的提升 System.out.println(c); 5 1 6 1 1 1.0
c语言中不允许对小数求余数,Java中允许,但是没有意义.
Java中关系运算符的结果永远都是 boolean类型的值(true,false)
c语言中得到的是0/1.
int a = 10; int b = 20; System.out.println(a == b); System.out.println(a != b); System.out.println(a < b); System.out.println(a > b); false true true false
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int a = 10; int b = 20; int c = 30; System.out.println(a < b && a < c ); System.out.println(a > b && a > c); System.out.println(a < b || a > c); System.out.println(! (a < b)); !优先级高于< > .计算机认为先计算 !a,在和 b进行<比较. 我们想要的是a和b进行比较,然后在进行!运算所以要加括号 true false true false
可以运用&& , | | 进行短路求值.
int a = 10; int b = 20; int c = 30; System.out.println(a > b && a < c ); //右边不会执行 短路求值 System.out.println(a < b || a > c); //右边会执行
