Declare a constant array

Question

I have tried  const ascii    quot abcdefghijklmnopqrstuvwxyz quot  const letter goodness   float32       0817  0149  0278  0425  1270  0223  0202   0609  0697  0015  0077  0402  0241  0675   0751  0193  0009  0599  0633  0906  0276   0098  0236  0015  0197  0007   const letter goodness       0817  0149  0278  0425  1270  0223  0202   0609  0697  0015  0077  0402  0241  0675   0751  0193  0009  0599  0633  0906  0276   0098  0236  0015  0197  0007   const letter goodness     float32    0817  0149  0278  0425  1270  0223  0202   0609  0697  0015  0077  0402  0241  0675   0751  0193  0009  0599  0633  0906  0276   0098  0236  0015  0197  0007    The first declaration and initialization works fine  but the second  third and fourth don t work  How can I declare and initialize a const array of floats

User · Answer

As others have mentioned  there is no official Go construct for this  The closest I can imagine would be a function that returns a slice  In this way  you can guarantee that no one will manipulate the elements of the original slice  as it is  quot hard-coded quot  into the array   I have shortened your slice to make it   shorter     func GetLetterGoodness     float32       return   float32    0817  0149  0278  0425  1270  0223

User · Answer

There is no such thing as array constant in Go   Quoting from the Go Language Specification  Constants      There are boolean constants  rune constants  integer constants  floating-point constants  complex constants  and string constants  Rune  integer  floating-point  and complex constants are collectively called numeric constants    A Constant expression  which is used to initialize a constant  may contain only constant operands and are evaluated at compile time   The specification lists the different types of constants  Note that you can create and initialize constants with constant expressions of types having one of the allowed types as the underlying type  For example this is valid   func main         type Myint int     const i1 Myint   1     const i2   Myint 2      fmt Printf   T  v n   i1  i1      fmt Printf   T  v n   i2  i2      Output  try it on the Go Playground    main Myint 1 main Myint 2   If you need an array  it can only be a variable  but not a constant   I recommend this great blog article about constants  Constants

User · Answer

An array isn t immutable by nature  you can t make it constant   The nearest you can get is   var letter goodness        float32   0817   0149   0278   0425   1270   0223   0202   0609   0697   0015   0077   0402   0241   0675   0751   0193   0009   0599   0633   0906   0276   0098   0236   0015   0197   0007     Note the       instead of     it ensures you get a  fixed size  array instead of a slice  So the values aren t fixed but the size is

User · Answer

From Effective Go   Constants in Go are just that   constant  They are created at compile time  even when defined as locals in functions  and can only be numbers  characters  runes   strings or booleans  Because of the compile-time restriction  the expressions that define them must be constant expressions  evaluatable by the compiler  For instance  1 lt  lt 3 is a constant expression  while math Sin math Pi 4  is not because the function call to math Sin needs to happen at run time   Slices and arrays are always evaluated during runtime  var TestSlice     float32   03   02  var TestArray    2 float32   03   02  var TestArray2        float32   03   02         tells the compiler to figure out the length of the array itself  Slices wrap arrays and are easier to work with in most cases  Instead of using constants  just make the variables unaccessible to other packages by using a lower case first letter  var ThisIsPublic    2 float32   03   02  var thisIsPrivate    2 float32   03   02   thisIsPrivate is available only in the package it is defined  If you need read access from outside  you can write a simple getter function  see Getters in golang

[arrays] Declare a constant array

Examples related to arrays

Examples related to go

Examples related to constants