如何使用存储在Go变量中的字符串键访问地图项？

Question

So I have a Go variable table map[string]string with some entries. I can access the map values using string keys as expected:

table["key"] // ok

But when I try to access the map with a string key retrieved from os.Stdin...

reader, _ := bufio.NewReader(os.Stdin)
key, _ := reader.ReadString('
') // type "key" (no quotations), press enter
value, _ := table[key] // no value :(

What could be wrong?

Answer 1

Make sure your key don't include the delimiter ' ' included by bytes.ReadString():

(and more generally, don't ignore the return values, especially the errors)

See this runnable(!) example on http://ideone.com/qgvsmF:

package main

import "bufio"
import "fmt"
import "os"

func main() {
    table := make(map[string]string)

    table["key1"] = "val1"
    table["key2"] = "val2"
    table["key3"] = "val3"

    fmt.Println("Enter a key (followed by Return):")
    reader := bufio.NewReader(os.Stdin)
    input, err := reader.ReadString('
')
    if err != nil {
        panic(err)
    }

    val, ok := table[input]
    fmt.Println("val for key '" + input + "' = '" + val + "'(" + fmt.Sprintf("%v", ok) + ")")
}

It will show a key equals to:

'key2
'

Remove the last character of your string, as in this runnable example:

input = strings.TrimRight(input, "
")

Output:

Enter a key (followed by Return):
val for key 'key2' = 'val2'(true)