i := 123
s := string(i)
s is 'E', but what I want is "123"
Please tell me how can I get "123".
And in Java, I can do in this way:
String s = "ab" + "c" // s is "abc"
how can I concat
two strings in Go?
strconv.Itoa(i)
(int to ASCII) to set an int to a string. See stackoverflow.com/a/62737936/12817546. strconv.Atoi(s)
(ASCII to int) to set a string to an int. See stackoverflow.com/a/62740786/12817546.
Use the strconv
package's Itoa
function.
For example:
package main
import (
"strconv"
"fmt"
)
func main() {
t := strconv.Itoa(123)
fmt.Println(t)
}
You can concat strings simply by +
'ing them, or by using the Join
function of the strings
package.
fmt.Sprintf("%v",value);
If you know the specific type of value use the corresponding formatter for example %d
for int
More info - fmt
%d
for int - this
fmt.Sprintf
, strconv.Itoa
and strconv.FormatInt
will do the job. But Sprintf
will use the package reflect
, and it will allocate one more object, so it's not an efficient choice.
https://i.stack.imgur.com/daIIz.png
It is interesting to note that strconv.Itoa
is shorthand for
func FormatInt(i int64, base int) string
with base 10
For Example:
strconv.Itoa(123)
is equivalent to
strconv.FormatInt(int64(123), 10)
You can use fmt.Sprintf or strconv.FormatFloat
For example
package main
import (
"fmt"
)
func main() {
val := 14.7
s := fmt.Sprintf("%f", val)
fmt.Println(s)
}
In this case both strconv
and fmt.Sprintf
do the same job but using the strconv
package's Itoa
function is the best choice, because fmt.Sprintf
allocate one more object during conversion.
https://i.stack.imgur.com/qd7EP.png
see https://play.golang.org/p/hlaz_rMa0D for example.
fmt.Sprintf
and strconv.iota
are similar in terms of ease of use and the above data shows iota to be faster with lower GC impact, it appears that iota
should be used in general when a single integer needs converting.
Converting int64
:
n := int64(32)
str := strconv.FormatInt(n, 10)
fmt.Println(str)
// Prints "32"
ok,most of them have shown you something good. Let'me give you this:
// ToString Change arg to string
func ToString(arg interface{}, timeFormat ...string) string {
if len(timeFormat) > 1 {
log.SetFlags(log.Llongfile | log.LstdFlags)
log.Println(errors.New(fmt.Sprintf("timeFormat's length should be one")))
}
var tmp = reflect.Indirect(reflect.ValueOf(arg)).Interface()
switch v := tmp.(type) {
case int:
return strconv.Itoa(v)
case int8:
return strconv.FormatInt(int64(v), 10)
case int16:
return strconv.FormatInt(int64(v), 10)
case int32:
return strconv.FormatInt(int64(v), 10)
case int64:
return strconv.FormatInt(v, 10)
case string:
return v
case float32:
return strconv.FormatFloat(float64(v), 'f', -1, 32)
case float64:
return strconv.FormatFloat(v, 'f', -1, 64)
case time.Time:
if len(timeFormat) == 1 {
return v.Format(timeFormat[0])
}
return v.Format("2006-01-02 15:04:05")
case jsoncrack.Time:
if len(timeFormat) == 1 {
return v.Time().Format(timeFormat[0])
}
return v.Time().Format("2006-01-02 15:04:05")
case fmt.Stringer:
return v.String()
case reflect.Value:
return ToString(v.Interface(), timeFormat...)
default:
return ""
}
}
fmt.Sprint
that does the same (except for time.Time
and jsoncrack.Time
(a package that will add dependencies I have never heard of) values).
Another option:
package main
import "fmt"
func main() {
n := 123
s := fmt.Sprint(n)
fmt.Println(s == "123")
}
https://golang.org/pkg/fmt#Sprint
package main
import (
"fmt"
"strconv"
)
func main(){
//First question: how to get int string?
intValue := 123
// keeping it in separate variable :
strValue := strconv.Itoa(intValue)
fmt.Println(strValue)
//Second question: how to concat two strings?
firstStr := "ab"
secondStr := "c"
s := firstStr + secondStr
fmt.Println(s)
}
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