# java syntax - decimal

Posted by mac25 on Sun, 06 Mar 2022 04:07:17 +0100

# Digit base

## Integer expansion

How to deal with binary, decimal, octal and hexadecimal expressions of "10"?

Binary plus 0b

decimal system

Octal plus 0

Hex plus 0x

give an example:

```int i = 10;
int i1 = 010; //Octal 0
int i2 = 0x10; // Hex 0x 0 ~ 9 A ~ F
int i3 = 0b10;
System.out.println(i);
System.out.println(i1);
System.out.println(i2);
System.out.println(i3);
```

## Floating point extension

How to express banking business?

Floating point numbers are finite and discrete, so they are approximate, but close to but not equal to.

Therefore, it is better not to compare with floating-point numbers:

Therefore, it is better not to compare with floating-point numbers:

Therefore, it is better not to compare with floating-point numbers:

give an example:

```float f = 0.1f;
double d = 1.0/10;
System.out.println(f==d); //false
System.out.println(f);
System.out.println(d);

float d1 = 232333334444443f;
float d2= d1 + 1;
System.out.println(d2);
System.out.println(d1==d2);
```

From the output result, f=d=0.1 F should be equal to d

d2=d1+1 D2 is not equal to D1;

However, according to the program judgment, f is not equal to d; d2 equals d1, which is why.

For the comparison of accurate data, we need to use the mathematical tool class: BigDecimal

## Character expansion

All characters are essentially numbers. Cast characters into integer numbers.

give an example:

```char c1 = 'a';
char c2 = 'in';
System.out.println(c1);
System.out.println(c2);
System.out.println((int)c1); //Cast line
System.out.println((int)c2); //Cast line
```
```//Code: byte 0 ~ 65536 of Unicode Table 2 to the 16th power of Excel 2;

// Range of Unicode table: U0000 ~ UFFFF
```

There is a Unicode table in the character and number conversion as the "translation table"

The corresponding output can be viewed with the following instructions:

```char c3 = '\u0061';//Escape character
System.out.println(c3); //a
```

# Digit base

## Integer expansion

How to deal with binary, decimal, octal and hexadecimal expressions of "10"?

Binary plus 0b

decimal system

Octal plus 0

Hex plus 0x

give an example:

```int i = 10;
int i1 = 010; //Octal 0
int i2 = 0x10; // Hex 0x 0 ~ 9 A ~ F
int i3 = 0b10;
System.out.println(i);
System.out.println(i1);
System.out.println(i2);
System.out.println(i3);
```

## Floating point extension

How to express banking business?

Floating point numbers are finite and discrete, so they are approximate, but close to but not equal to.

Therefore, it is better not to compare with floating-point numbers:

Therefore, it is better not to compare with floating-point numbers:

Therefore, it is better not to compare with floating-point numbers:

give an example:

```float f = 0.1f;
double d = 1.0/10;
System.out.println(f==d); //false
System.out.println(f);
System.out.println(d);

float d1 = 232333334444443f;
float d2= d1 + 1;
System.out.println(d2);
System.out.println(d1==d2);
```

From the output result, f=d=0.1 F should be equal to d

d2=d1+1 D2 is not equal to D1;

However, according to the program judgment, f is not equal to d; d2 equals d1, which is why.

For the comparison of accurate data, we need to use the mathematical tool class: BigDecimal

## Character expansion

All characters are essentially numbers. Cast characters into integer numbers.

give an example:

```char c1 = 'a';
char c2 = 'in';
System.out.println(c1);
System.out.println(c2);
System.out.println((int)c1); //Cast line
System.out.println((int)c2); //Cast line
```
```//Code: byte 0 ~ 65536 of Unicode Table 2 to the 16th power of Excel 2;

// Range of Unicode table: U0000 ~ UFFFF
```

There is a Unicode table in the character and number conversion as the "translation table"

The corresponding output can be viewed with the following instructions:

```char c3 = '\u0061';//Escape character
System.out.println(c3); //a
```

Common escape characters include:

```//Transfer character
// \t tab
// \n line feed
// \r enter
// \b backspace
System.out.println("Hello\tWorld");
```

## Boolean extension

boolean flag = true;

if (flag==true) {} is the same as if (flag) {}.
Common escape characters include:

```//Transfer character
// \t tab
// \n line feed
// \r enter
// \b backspace
System.out.println("Hello\tWorld");
```

## Boolean extension

boolean flag = true;

if (flag==true) {} is the same as if (flag) {}.