Create global map variables

Question

I need a little help regarding creating a global map variable in Go. What I have done is as follows:

package ... import( ... ) ... type ir_table struct{     symbol      string     value       string } var ir_MAP map[int]ir_table 

Since I am not initializing the map, I am getting a nil pointer dereference error. What must I do to use this variable globally? Or, if this is not a correct way to do this, please guide me.

Answer 1

You need to initialize it with an empty map:

var ir_MAP = map[int]ir_table{} 

or, as "the system" suggested:

var ir_MAP = make(map[int]ir_table) 

The problem is that the zero value of a map is nil, and you can't add items to a nil map.

Answer 2

You can directly initialize a map like this:

var Romans = map[byte]int{     'I': 1,     'V': 5,     'X': 10,     'L': 50,     'C': 100,     'D': 500,     'M': 1000, }