英文:
How do I check if the user has entered a null value in Go?
问题
以下是翻译好的内容：
reader := bufio.NewReader(os.Stdin)
fmt.Print("输入文本：")
text, _ := reader.ReadString('\n')
fmt.Println("你好", text)
我该如何检查用户是否输入了空值，代码应该放在哪里？注意 - 我已经尝试过检查长度= 0和= ""，但它们似乎不起作用。
请提供另一种方法。谢谢！
英文:
reader := bufio.NewReader(os.Stdin)
fmt.Print("Enter text: ")
text, _ := reader.ReadString('\n')
fmt.Println("Hello",text)
How do I check if the user has entered a null value and where do I put the code? Note - I've already tried checking the length = 0 and = " " but, they don't seem to be working.
Please suggest an alternative way for doing this. Thanks!
答案1
得分: 6
bufio.Reader.ReadString() 返回一个包含分隔符的字符串，对于换行符\n来说也是如此。
如果用户没有输入任何内容，只是按下了<kbd>Enter</kbd>键，ReadString() 的返回值将是 "\n"，因此你需要将结果与 "\n" 进行比较以检查空输入：
reader := bufio.NewReader(os.Stdin)
fmt.Print("Enter text: ")
text, err := reader.ReadString('\n')
if err != nil {
panic(err) // 不要忘记检查和处理返回的错误！
}
if text == "\n" {
fmt.Println("No input!")
} else {
fmt.Println("Hello", text)
}
更好的替代方法是使用 strings.TrimSpace()，它会删除前导和尾随的空白字符（包括换行符；如果有人输入两个空格然后按下<kbd>Enter</kbd>键，这个解决方案也会过滤掉）。如果在调用 strings.TrimSpace() 之前将其与空字符串 "" 进行比较：
text = strings.TrimSpace(text)
if text == "" {
fmt.Println("No input!")
} else {
fmt.Println("Hello", text)
}
英文:
bufio.Reader.ReadString() returns a string that also contains the delimeter, in this case the newline character \n.
If the user does not enter anything just presses the <kbd>Enter</kbd> key, the return value of ReadString() will be "\n", so you have to compare the result to "\n" to check for empty input:
reader := bufio.NewReader(os.Stdin)
fmt.Print("Enter text: ")
text, err := reader.ReadString('\n')
if err != nil {
panic(err) // Don't forget to check and handle returned errors!
}
if text == "\n" {
fmt.Println("No input!")
} else {
fmt.Println("Hello", text)
}
An even better alternative would be to use strings.TrimSpace() which removes leading and trailing white space characters (newline included; it isn't a meaningful name if someone inputs 2 spaces and presses <kbd>Enter</kbd>, this solution also filters that out). You can compare to the empty string "" if you called strings.TrimSpace() prior:
text = strings.TrimSpace(text)
if text == "" {
fmt.Println("No input!")
} else {
fmt.Println("Hello", text)
}
答案2
得分: 0
// 我迄今为止编写的最好的算法
package main
import (
"bufio"
"fmt"
"os"
)
func main() {
欢迎()
sina := 获取信息()
fmt.Printf("%v", sina)
再见()
}
func 欢迎() {
fmt.Println("欢迎来到这个程序...[*]")
}
func 获取信息() string {
reader := bufio.NewReader(os.Stdin)
fmt.Print("输入名字: ")
firstName, _ := reader.ReadString('\n')
if len(firstName) >= 5 {
return firstName
}
for {
fmt.Print("名字必须超过3个字符: ")
firstName, _ := reader.ReadString('\n')
if len(firstName) < 5 {
continue
} else if len(firstName) >= 5 {
return firstName
}
}
}
func 再见() {
fmt.Println(" ")
fmt.Println(" ")
fmt.Println(" [*]----------------------[*] ")
fmt.Println(" [*]----谢谢再见----[*] ")
fmt.Println(" [*]----------------------[*] ")
fmt.Println(" ")
fmt.Println(" ")
}
请注意，我只翻译了代码部分，其他内容不做翻译。
英文:
// The best algorithm I have written so far
package main
import (
"bufio"
"fmt"
"os"
)
func main() {
Wellcome()
sina := get_Informations()
fmt.Printf("%v", sina)
Goodbye()
}
func Wellcome() {
fmt.Println("Welcome to this Program ...[*]")
}
func get_Informations() (string){
reader := bufio.NewReader(os.Stdin)
fmt.Print("Enter First-Name: ")
firstName, _ := reader.ReadString('\n')
if len(firstName) >= 5 {
return firstName
}
for {
fmt.Print("First-Name must be more than 3 characters: ")
firstName, _ := reader.ReadString('\n')
if len(firstName) < 5 {
continue
}else if len(firstName) >=5{
return firstName
}
}
}
func Goodbye() {
fmt.Println(" ")
fmt.Println(" ")
fmt.Println(" [*]----------------------[*] ")
fmt.Println(" [*]----THANKS.GOODBYE----[*] ")
fmt.Println(" [*]----------------------[*] ")
fmt.Println(" ")
fmt.Println(" ")
}
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