https://golang.k5kc.com/categories/go-types/Recent content in go-types on GolangHugo -- gohugo.ioen-usSun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/2.basic-data-types/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/2.basic-data-types/Following are the basic data types in Go: Numeric // Integer Types uint8 // Unsigned 8-bit integers (0 to 255) uint16 // Unsigned 16-bit integers (0 to 65535) uint32 // Unsigned 32-bit integers (0 to 4294967295) uint64 // Unsigned 64-bit integers (0 to 18446744073709551615) int8 // Signed 8-bit integers (-128 to 127) int16 // Signed 16-bit integers (-32768 to 32767) int32 // Signed 32-bit integers (-2147483648 to 2147483647) int64 // Signed 64-bit integers (-9223372036854775808 to 9223372036854775807) // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Floating Types float32 // IEEE-754 32-bit floating-point numbers float64 // IEEE-754 64-bit floating-point numbers complex64 // Complex numbers with float32 real and imaginary parts complex128 // Complex numbers with float64 real and imaginary parts // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Other Numeric Types byte // same as uint8 rune // same as int32 uint // 32 or 64 bits int // same size as uint uintptr // an unsigned integer to store the uninterpreted bits of a pointer value Handling Overflows At compile time, a Go compiler can catch overflow errors.https://golang.k5kc.com/2020/08/16/1.data-types-intro/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/1.data-types-intro/There are following data types in Go: Basic type: Numbers, strings, and booleans come under this category. Aggregate type: Array and structs come under this category. Reference type: Pointers, slices, maps, functions, and channels come under this * category. Interface typehttps://golang.k5kc.com/2020/08/16/mutability/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/mutability/In Go, only constants are immutable. However because arguments are passed by value, a function receiving a value argument and mutating it, won’t mutate the original value. package main import "fmt" type Artist struct { Name, Genre string Songs int } func newRelease(a Artist) int { a.Songs++ return a.Songs } func main() { me := Artist{Name: "Matt", Genre: "Electro", Songs: 42} fmt.Printf("%s released their %dth song\n", me.Name, newRelease(me)) fmt.Printf("%s has a total of %d songs", me.https://golang.k5kc.com/2020/08/16/named-vs-unnamed-types/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/named-vs-unnamed-types/Types in Go are divided into 2 categories: named and unnamed. Besides predeclared types (such as int, rune, etc), you can also define named type yourself. E.g.: type mySlice []int Unnamed types are defined by type literal. I.e., []int is an unnamed type. According to Go spec, there is an underlying type of every type: Each type T has an underlying type: If T is one of the predeclared boolean, numeric, or string types, or a type literal, the corresponding underlying type is T itself.https://golang.k5kc.com/2020/08/16/3.string/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/3.string/In Go, string is an immutable array of bytes. So if created, we can’t change its value. E.g.: package main func main() { s := "Hello" s[0] = 'h' } The compiler will complain: cannot assign to s[0] To modify the content of a string, you could convert it to a byte array. But in fact, you do not operate on the original string, just a copy: package main import "fmt" func main() { s := "Hello" b := []byte(s) b[0] = 'h' fmt.https://golang.k5kc.com/2020/08/16/1.struct/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/1.struct/Intro A struct is a collection of fields/properties. You can define new types as structs or interfaces. If you are coming from an object-oriented background, you can think of a struct to be a light class that supports composition but not inheritance. Structs are blueprints — They are fixed and created at compile-time, but struct values fill them in runtime.. It’s like a class in OOP languages. Groups related data in a single type.https://golang.k5kc.com/2020/08/16/4.type-conversion/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/4.type-conversion/The expression T(v) converts the value v to the type T. Some numeric conversions: var i int = 42 var f float64 = float64(i) var u uint = uint(f) Or, put more simply: i := 42 f := float64(i) u := uint(f) Go assignment between items of different type requires an explicit conversion which means that you manually need to convert types if you are passing a variable to a function expecting another type.https://golang.k5kc.com/2020/08/16/pointers/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/pointers/Go has pointers, but no pointer arithmetic. Struct fields can be accessed through a struct pointer. The indirection through the pointer is transparent (you can directly call fields and methods on a pointer). Note that by default Go passes arguments by value (copying the arguments), if you want to pass the arguments by reference, you need to pass pointers (or use a structure using reference values like slices (Section 4.2) and maps (Section 4.https://golang.k5kc.com/2020/08/16/methods-with-struct-and-interface/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/methods-with-struct-and-interface/Methods enhance types with additional behavior. Methods of the type are called Method Set. To attach method to a type : // Syntax // “varName Type” is called a “receiver” func (varName Type) funcName() { // Code } // Example // “book” is a struct here func (b book) printBook() { fmt.Println(b.title, b.price) } - A `receiver` is nothing but method's `input parameters` written `before` a `method name`. - A `method` belongs to a `single type`.https://golang.k5kc.com/2020/08/16/nil-values/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/nil-values/https://golang.k5kc.com/2020/08/16/printf-sprintf-formatting/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/printf-sprintf-formatting/Following formatting can be used with fmt.Printf as well as fmt.Sprintf: // String and slice of bytes %s // the uninte­rpreted bytes of the string or slice %q // a double­-quoted string safely escaped with Go syntax %x // base 16, lower-­case, two characters per byte %X // base 16, upper-­case, two characters per byte // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Boolean %t // the word true or false // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // General %v // The value in a default format.https://golang.k5kc.com/2020/08/16/5.type-assertion-and-type-switch/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/5.type-assertion-and-type-switch/If we have a value and want to convert it to another or a specific type (in case of interface{}), we can use type assertion. A type assertion takes a value and tries to create another version in the specified explicit type. This is how we can use type assertion: x.(T) x is the variable whose type must be interface, and T is the type which you want to check. For example:https://golang.k5kc.com/2020/08/16/zero-values/Sun, 16 Aug 2020 00:10:00 +0530https://golang.k5kc.com/2020/08/16/zero-values/When a variable is declared and it isn’t assigned any value at the time of declaration, Go will assign a zero value to it based on it’s variable type. Type of a variable decides what a zero value to it will take initially when declared (and if it isn’t assigned any value at the time of declaration). // Zero Values assigned to variables by Go when they are declared and not assigned any values at the time of declaration.