英文:
Question about indexing characters of strings
问题
下面是我创建的程序，用于理解在Go语言中如何对字符串字符进行索引：
package main
import "fmt"
func main() {
vendor1 := "Cisco"
fmt.Println(vendor1[0])
fmt.Println(vendor1[1:4])
fmt.Println(vendor1[1:])
fmt.Println(vendor1[:])
}
输出结果：
C:\Golang\VARIABLE> go run .\variable.go
67
isc
isco
Cisco
让我感到困惑的是，Println(vendor1[0]) 返回的是数字 67 而不是 C，为什么会这样？为什么它与 Println(vendor1[1:4])、Println(vendor1[1:]) 和 Println(vendor1[:]) 返回的期望字符不同？
英文:
Below is the program I created to understand how indexing of string characters work in Go:
package main
import "fmt"
func main() {
vendor1 := "Cisco"
fmt.Println(vendor1[0])
fmt.Println(vendor1[1:4])
fmt.Println(vendor1[1:])
fmt.Println(vendor1[:])
}
Output:
C:\Golang\VARIABLE> go run .\variable.go
67
isc
isco
Cisco
What puzzled me is that Println(vendor1[0]) returns the number '67' instead of 'C', why is that so? Why it is different from Println(vendor1[1:4]) , Println(vendor1[1:]) and Println(vendor1[:]) which all return the desired characters?
答案1
得分: 3
Index expressions（索引表达式）与slice expressions（切片表达式）不是同一回事，请不要混淆它们。
索引操作返回的是一个byte类型，它是uint8的类型别名，而Println函数只是简单地打印出这个无符号整数。
切片操作返回的是一个字符串，这就是为什么Println输出的是文本。
英文:
Index expressions are not the same thing as slice expressions, don't conflate them.
Indexing, as opposed to slicing, returns a byte which is a type alias of uint8, and Println simply prints out the unsigned integer.
Slicing returns a string, which is why Println outputs a text.
答案2
得分: 1
要打印索引为0的值，请改用fmt.Printf("%c\n", vendor1[0])而不是fmt.Println(vendor1[0])，对于其他三个值，您可以使用fmt.Printf()和%s，因为它们是字符串。我修改了您的代码如下：
package main
import (
"fmt"
)
func main() {
vendor1 := "Cisco"
fmt.Printf("%c\n", vendor1[0])
fmt.Printf("%s\n", vendor1[1:4])
fmt.Printf("%s\n", vendor1[1:])
fmt.Printf("%s\n", vendor1[:])
}
输出：
C
isc
isco
Cisco
英文:
To print the value at index 0 use fmt.Printf("%c\n", vendor1[0]) instead of fmt.Println(vendor1[0]),for the other three values you can use %s with fmt.Printf() since they are string.I modified your code as follows:
package main
import (
"fmt"
)
func main() {
vendor1 := "Cisco"
fmt.Printf("%c\n", vendor1[0])
fmt.Printf("%s\n", vendor1[1:4])
fmt.Printf("%s\n", vendor1[1:])
fmt.Printf("%s\n", vendor1[:])
}
Output:
C
isc
isco
Cisco
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