In Go, what is the best strategy for converting int64
to int
? I am having difficulty comparing the two
package main
import (
"math"
"strings"
"strconv"
)
type largestPrimeFactor struct {
N int
Result int
}
func main() {
base := largestPrimeFactor{N:13195}
max := math.Sqrt(float64(base.N))
maxStr := strconv.FormatFloat(max, 'E', 'G', 64)
maxShift := strings.Split(maxStr, ".")[0]
maxInt, err := strconv.ParseInt(maxShift, 10, 64)
if (err != nil) {
panic(err)
}
on this next line
for a := 2; a < maxInt; a++ {
if isPrime(a) {
if base.N % a == 0 {
base.Result = a
}
}
}
println(base)
}
func isPrime(n int) bool {
flag := false
max := math.Sqrt(float64(n))
maxStr := strconv.FormatFloat(max, 'E', 'G', 64)
maxShift := strings.Split(maxStr, ".")[0]
maxInt, err := strconv.ParseInt(maxShift, 10, 64)
if (err != nil) {
panic(err)
}
for a := 2; a < maxInt; a++ {
if (n % a == 0) {
flag := true
}
}
return flag
}
You convert them with a type "conversion"
var a int
var b int64
int64(a) < b
When comparing values, you always want to convert the smaller type to the larger. Converting the other way will possibly truncate the value:
var x int32 = 0
var y int64 = math.MaxInt32 + 1 // y == 2147483648
if x < int32(y) {
// this evaluates to false, because int32(y) is -2147483648
Or in your case to convert the maxInt
int64
value to an int
, you could use
for a := 2; a < int(maxInt); a++ {
which would fail to execute correctly if maxInt
overflows the max value of the int
type on your system.