A = 65  
B =66  
C = 67  
.  
.  
.  
.  
.  
Z = 90

ASCII value of B = ASCII value of A + 1
ASCII value of c = ASCII value of A + 2

package main

// fmt package provides the function to print anything
import "fmt"

func main() {
   // declaring the variable which is an ASCII value of A
   var startingASCIINumber int = 65

   fmt.Println("Printing the alphabets from A to Z using a loop.")

   // printing the Alphabet from A to Z using for loop and
   // ASCII value concept
   for i := 0; i < 26; i++ {
      fmt.Print(string(rune(startingASCIINumber+i)), " ")
   }
}

Printing the alphabets from A to Z using a loop.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z