int to string
s := strconv.Itoa(123)
int64 to string
var n int64 = 123 s := strconv.FormatInt(n, 10) // s == "123" (decimal)
var n int64 = 123 s := strconv.FormatInt(n, 16) // s == "7b" (hexadecimal)
string to int
s := "123" n, err := strconv.Atoi(s)
string to int64
s := "123" n, err := strconv.ParseInt(s, 10, 64)