# Perl ABC

1. Perl
2. Syntax
3. here

## Numeric literals - Representation of numbers in source code

The representation of numbers in the source code is called number literals . Numeric literals can be written as follows.

#### integer

Numbers that are not enclosed in quotes or double quotes are interpreted by Perl as numeric literals.

```my \$num1 = 1;

# Negative number
my \$num2 = -1;
```

#### Digit separator expression

If an underscore is included in a numeric literal, it will be ignored. The notations 1_000_000 and 1000000 are equivalent. Underscores can be used to make large numbers easier to read.

```# You can use _ as a digit separator.
my \$num3 = 1_000_000;
```

#### Decimal (floating point)

If it contains a. (Dot), it is interpreted as a decimal. It is the same as the notation in mathematics. A few Perls are double precision floating point.

```# Decimal point
my \$num4 = 1.33;
```

#### Minority exponential notation

You can use exponential notation to represent a small number of numbers. 1.3E3 is equivalent to 1300. 1.3E-3 is equivalent to 0.0013.

```# 1.3 x 10 cubed
my \$num5 = 1.3E3;

# 1.3 x 10 to the -3rd power
my \$num6 = 1.3E-3;
```

#### Binary number

You can specify a numerical value in binary by prefixing it with 0b.

```my \$num_bin = 0b1111;
```

#### Octal number

If you add 0 to the beginning, you can specify a numerical value in octal.

```my \$num_oct = 0777;
```

You can specify a number in hexadecimal by prefixing it with 0x.

```my \$num_hex = 0xFFFF;
```

#### What are the numbers in Perl?

The numbers in Perl are explained in detail below.

### Example program

This is an example program that uses numerical literals.

```use strict;
use warnings;

my \$num1 = 1;

# Negative number
my \$num2 = -1;

# You can use _ as a digit separator.
my \$num3 = 1_000_000;

# Decimal
my \$num4 = 1.33;

# Minority exponential notation 1.3 x 10 cubed
my \$num5 = 1.3E3;

# 1.3 x 10 to the -3rd power
my \$num6 = 1.3E-3;

print "\\$num1 = \$num1\n";
print "\\$num2 = \$num2\n";
print "\\$num3 = \$num3\n";
print "\\$num4 = \$num4\n";
print "\\$num5 = \$num5\n";
print "\\$num6 = \$num6\n";
```