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Day07 type of mathematical operator automatic conversion relational operator bitwise operator blind date math
2022-07-05 07:36:00 【33 year old Java enthusiast】
Operator understanding
Operator
Arithmetic operator :
- +
- -
- multiply
- /
- %( Take the remainder ) Modular arithmetic
- ++
- –
public class demo01{
public static void main(String[] args){
int a =10;
byte b =20;
System.out.println(a+b); // The result type is int
// Just add, subtract, multiply and divide integers , without long The type of , By default, it will be uniformly converted to int type
long d =1237192381273891723891289L;
byte e = 12;
System.out.println(d+e); // The result type is LONG
// As long as there is long type , The result will be converted to long type
// As long as there is double type , The result will be converted to double type
/* Be careful : If the result shows floating point numbers , If there is no conversion type, you will get 0 Result . */
//System.out.println(a/b);// The actual result is 0.5, The result is 0, Because floating point numbers are not converted
System.out.println(a/(double)b); // Correct expression
}
}
Automatic conversion rules for calculation :
- Just add, subtract, multiply and divide integers , without long The type of , By default, it will be uniformly converted to int type
- As long as there is long type , The result will be converted to long type
- As long as there is double type , The result will be converted to double type
word :cast transformation
idea shortcuts :ctrl+d Quickly copy the previous line
package operator;
public class demoday01 {
public static void main(String[] args) {
int a = 10;
byte b =20;
long c=100L;
double d =3.14;
System.out.println(a+b); // Floating point numbers and long type , The default conversion is int
System.out.println(a-c); // appear long type , Automatic conversion to long type
System.out.println(c*d); // Floating point numbers appear , Automatically convert to floating point number type , Due to discrete type , The suffix will be inaccurate
System.out.println(a/(double)b); // When floating-point numbers appear, we have to convert them to floating-point numbers to calculate , Otherwise, we will only get 0
short g1 = 5;
short g2 = 2;
System.out.println(g1/g2);//2 int type , There will be no floating point numbers
System.out.println(g1%g2);//1 Modular arithmetic Take the remainder
System.out.println(g1/(double)g2);//2.5
}
}
Operation rules of self increase and self decrease
a++ Follow ++a The difference between
b=a++ amount to ,b=a, then a=a+1
b=++a amount to a=a+1, Then it's b=a
Assign a value before the equal sign , The equal sign is followed by calculation and then assignment
package operator;
public class demo03Day06 {
public static void main(String[] args) {
int a = 2;
int b =a++; // It is equivalent to calculating first b=a, then a=a+1
int c =++a; // amount to a=a+1, then c =a
System.out.println(b); //2
System.out.println(c); //4
}
}
Assignment operator : =
Relational operator :
- >
- <
- >=
- <=
- ==
- !=
- instanceof
package operator;
public class demo02Day06 {
public static void main(String[] args) {
int a = 1;
int b = 1;
int c = 2;
byte d = 2;
double e =2.123123;
float f = 2.123123f;
short g =5;
System.out.println(a==b);//true
System.out.println(a==c);//false
System.out.println(d==c);//true
System.out.println(d!=e);//true
System.out.println(f==e);//false Accuracy error Avoid floating-point comparisons
System.out.println(c<=e);//true Avoid floating-point comparisons
System.out.println(g/c);// The type is not converted =2
// Modular arithmetic , That is, take the remainder
System.out.println(g/(double)c);// correct
System.out.println(g%c);// Modular arithmetic result =1
}
}
Logical operators
- && ( And )and
- || ( or )or
- ! ( Not )not Take the opposite
package operator;
public class demo04Day06 {
public static void main(String[] args) {
boolean a = true;
boolean b = false;
boolean c =true;
System.out.println(a&&b);// Two for the truth
System.out.println(a||b);// One of them is true
System.out.println(!(a&&b));// Just one of them is fake , It's true . As long as both are true , It's fake .
System.out.println(!(a&&c));// As long as both are true , It's fake . Just one of them is fake , It's true .
// Short-circuit operation
int d =5;
boolean f = false;
System.out.println(f&&(d>d++));// As long as the first part is fake , Stop the following operations
System.out.println(d);// Originally d++ What is calculated first can be equal to 6, The condition is true . But if the first part is false, just quit the operation
}
}
An operator ( Binary is used )
A =0011 0101
B=1001 0010
A&B =0001 ,1000 //and, If the top and bottom are the same, it is 1, Or for 0
A|B =1011 0111 // perhaps , If the next one is 1 for 1
A^B =0101 1000 // Take the opposite , If the upper and lower are the same , Then for 1, No is 0
~A =1100 1010 // Take the opposite
2<<3 2 Move right 3 position , amount to 2 multiply 2 multiply 2 multiply 2
0000 0000 by 0
0000 0001 by 1
0000 0010 by 2, Move three places to the right 0001 0000
0000 0011 3
0000 0100 4
0000 0101 5
0000 0110 6
0000 0111 7
0000 1000 8
0001 0000 by 16
Extracurricular expansion
java Calculating power , How many powers of numbers .
Math yes java Important mathematical operation Library
quote Math Library pow Calculation .
package operator;
public class demo03Day06 {
public static void main(String[] args) {
double d =Math.pow(2,4); //2 The fourth power of , Output as floating point number
System.out.println(d);
}
}
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