Course Content

• Functions are the building blocks of a program.
• Functions are used to organize code.
• Functions are used to avoid code duplication.
• Functions are used to make code more readable.

package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}

• Packages are used to organize code.
• Packages are used to avoid name conflicts.
• Packages are used to make code more readable.

package main

All Go programs on the first line of the file must have a package declaration. The package declaration is used to define which package the file belongs to. The package declaration is used to organize code.

package learn

The package declaration is used to define which package the file belongs to. The package declaration is used to organize code.

• reserved package keyword main is used to create an executable program.
• You can not have more than one main package in a Go program.

• Go modules are used to manage dependencies.
• 1 module consists of multiple packages.

Go comes with a couple of built-in basic types:

• bool: for booleans true and false
• int: Numbers without decimal places
• float64: Numbers with decimal places
• string: text values(created with double quotes or backticks)

There are also some more complex types:

• uint: unsigned integer(only positive or zero) Unsigned means that the integer can only represent non-negative numbers.
  • uint8: 8-bit unsigned integer(0 to 255)
  • uint16: 16-bit unsigned integer(0 to 65535)
  • uint32: 32-bit unsigned integer(0 to 4294967295)
  • uint64: 64-bit unsigned integer(0 to 18446744073709551615)
• int32: 32-bit signed integer(-2147483648 to 2147483647)
• int64: 64-bit signed integer(-9223372036854775808 to 9223372036854775807)
• rune: represents a Unicode code point
• byte: alias for uint8
• complex64: complex numbers with float32 real and imaginary parts
• complex128: complex numbers with float64 real and imaginary parts
• uintptr: an unsigned integer to store the uninterpreted bits of a pointer value
• nil: the zero value for pointers, interfaces, maps, slices, channels, and functions

In Go value types come with a "null value" which is the value stored in a variable if no other value has been explicitly assigned to it. The null value for a type is the zero value for that type.

• 0 for numeric types
• false for the boolean type
• "" for strings
• nil for pointers, functions, interfaces, slices, channels, and maps
• 0.0 for floating-point numbers
• 0+0i for complex numbers
• '\u0000' for runes
• [] for arrays and slices
• struct{}{} for structs
• chan struct{}{} for channels

• What we are building: Profit Calculator
• What are the inputs: revenue, expenses, taxRate
• Calculates earnings before tax: revenue - expenses
• Calculates earnings after tax: earnings before tax - (earnings before tax * taxRate)
• Calculate ratio: ebt/profit
• Output: earnings before tax, profit, ratio