如何转换函数类型? [关闭]
问题描述:
I want to use upCase as a variable in expend, But it said "Cannot use 'upCase(s1)'(type string) as type func(string) string. how can I to convert upCase type? Or what do I need do to make the wrong disappear?
package main
import (
"fmt"
"strings"
)
func main() {
s := "test func"
s1 := ""
test := expand(s, upCase(s1))
fmt.Print(test)
}
func expand(s string, f func(string) string) string {
s1 := "test"
var s2 string
if strings.Contains(s, s1) {
// todo 字符串中s1的值更改为f(s1)的值
s1 = f(s1)
strings.Replace(s1, s, s2, -1)
} else {
return ""
}
return s2
}
func upCase(s string) string {
s = strings.ToUpper(s)
return s
}
我想将upCase用作支出变量,但是它说“不能使用'upCase(s1)'( 如何转换upCase类型?或者我需要怎么做才能使错误消失? p>
包main
import(
“ fmt”
“ strings”
)
func main(){
s:=“ test func”
s1:=“”
test:= expand(s,upCase( s1))
fmt.Print(test)
}
func expand(s string,f func(string)string)string {
s1:=“ test”
var s2 string
if strings.Contains( s,s1){
// todo字符串中s1的值更改为f(s1)的值
s1 = f(s1)
字符串。替换(s1,s,s2,-1)
} 否则{
返回“”
}
返回s2
}
func upCase(s string)string {
s = strings.ToUpper(s)
返回s
}
code> pre>
div>
答
You are calling the upCase
function in your call to expand
(so it returns a string that you pass to your expand
function). You need to pass in the function:
test := expand(s, upCase)
Your current code test := expand(s, upCase(s1))
is the same as doing:
v := upCase(s1)
test := expand(s, v)
I.e, you are just calling upCase(s1)
that returns a string, and you pass that string to expand
, which expects a function, not a string as its 2. argument.