package day03; /* * 关系运算 */ public class Demo04 { public static void main(String[] args) { char c = 'A'; boolean b = c>'D';//false boolean b1 = c<='Z';//true char ch = 'A';//65 65>=48 65< = 57 boolean isNumber = ch>='0' && ch <='9'; //判断一个字符是否是数字字符("0"~'9') System.out.println(isNumber); ch = '6'; isNumber = ch>='0' && ch <='9'; System.out.println(isNumber);//true } }
package day03; /* * 短路逻辑运算 */ public class Demo05 { public static void main(String[] args) { int age = 65; char sex = '男'; //如果sex=='女'计算结果是true,就能够确定整个逻辑&&运算的结果 //age++>60运算就不在执行了。 if(sex=='女'&& age++>60){ System.out.println("欢迎光临!"); } System.out.println(age);//65表示(age++>60)没有执行 //&&是短路逻辑,大多使用短路逻辑&& //&是非短路逻辑 } }
package day03; import java.util.Scanner; /* * 3元运算 */ public class Demo06 { public static void main(String[] args) { Scanner console = new Scanner(System.in); // String s = console.nextLine(); // char c1 = s.charAt(0); // char c2 = s.charAt(1); // char c3 = s.charAt(2); System.out.print("输入用空格隔开的3个数: "); int a = console.nextInt(); int b = console.nextInt(); int c = console.nextInt(); //计算了ab中的最大值 int max = a>b ? a: b;//找出ab中间最大的数max max = max > c ? max : c;//找出max c中间最大的数 //就是abc中间最大的数 System.out.println("最大是: "+ max); } }
package day03; /* * 计算分页数量 * */ public class Demo07 { public static void main(String[] args) { int rows = 36; int size = 10; int pages = (rows%size==0) ? (rows/size): (rows/size+1); System.out.println(pages); } }
package day03; /* * 赋值运算 */ public class Demo08 { public static void main(String[] args) { int a; int b; int c; c = a = b = 3; //c = (a = (b=3)); c = a+(b=1); System.out.println(a+","+b+","+c); a = 1; b+=a;//等价 b=b+a b*=a; b/=a; b%=a; } }
package day03; /* * 注:闰年的判断公式为: * 1 年份能被4整除,且不能被100整除的是闰年 * 2 年份能被400整除的是闰年 */ public class Demo10 { public static void main(String[] args) { int year=2004; boolean isLeapYear; //年份能被4整除 year%4 == 0 //不能被100整除的 !(year%100 == 0) 或者(year%100 != 0) // 1 (year % 4 ==0)&& !(year%100)==0) // 2 year %400 ==0 //总的表达式1 || 2 isLeapYear = ((year%4==0) && !(year%100==0))|| year % 400 ==0; if(isLeapYear){ System.out.println(year+"是闰年"); }else{ System.out.println(year+"不是闰年"); } } }
package day03; public class Demo09 { public static void main(String[] args) { System.out.println("a"+'b');//ab System.out.println('a'+'b');//195 } }