reading from stdin in go by example
Jul 27, 2025 am 04:15 AM
Use fmt.Scanf to read formatted input, suitable for simple structured data, but strings are cut off when encountering spaces; 2. It is recommended to use bufio.Scanner to read line by line, supports multi-line input, EOF detection and pipeline input, and can handle scanning errors; 3. Use io.ReadAll(os.Stdin) to read all inputs at once, suitable for processing large chunks of data or file streams; 4. Real-time key response requires third-party libraries such as golang.org/x/term, and bufio is sufficient for conventional scenarios; practical suggestions: use fmt.Scan for interactive simple input, use bufio.Scanner for line input or pipeline, use io.ReadAll for large chunks of data, and always handle errors to avoid silence failure.
In Go, reading data from standard input ( stdin ) is a common requirement, such as reading user input or processing pipeline data. Here are some common and practical methods that combine Go by Example 's style to show how to read content from stdin .
1. Read formatted input using fmt.Scanf
Suitable for reading structured inputs, such as single numbers or strings.
package main
import "fmt"
func main() {
var name string
var age int
fmt.Print("Enter name and age: ")
fmt.Scanf("%s %d", &name, &age)
fmt.Printf("Hello %s, you are %d years old.\n", name, age)
}?? Note:
Scanfwill stop reading the string when encountering spaces, which is suitable for simple scenarios.
2. Use bufio.Scanner to read line by line (recommended)
This is the most commonly used method, suitable for reading multiple lines of input or processing EOF (such as pipeline input).
package main
import (
"bufio"
"fmt"
"os"
)
func main() {
scanner := bufio.NewScanner(os.Stdin)
fmt.Println("Enter text (Ctrl D to end):")
for scanner.Scan() {
line := scanner.Text()
if line == "exit" {
break
}
fmt.Printf("You entered: %s\n", line)
}
if err := scanner.Err(); err != nil {
fmt.Fprintln(os.Stderr, "reading standard input:", err)
}
}? Pros:
- Supports reading by line
- Compatible with terminal inputs and pipelines (such as
echo "hello" | go run main.go)- Detectable
EOF(Ctrl D on Unix, Ctrl Z on Windows)
3. Read all inputs at once (suitable for processing files or large chunks of data)
Read the entire stdin content using io.ReadAll .
package main
import (
"fmt"
"io"
"os"
)
func main() {
fmt.Println("Paste content (Ctrl D to finish):")
data, err := io.ReadAll(os.Stdin)
if err != nil {
fmt.Fprintln(os.Stderr, "Error reading input:", err)
Return
}
fmt.Printf("Read %d bytes:\n%s", len(data), data)
}? Applicable scenarios:
- Process complete input of JSON, configuration files, etc.
- Use with pipelines, such as
cat data.txt | go run main.go
4. Read single characters or non-buffered input
If you need to respond to keys in real time (such as games or interactive tools), you can use system-level calls, but the standard library does not directly support it. You can use third-party libraries such as golang.org/x/term .
However, for normal stdin reading, bufio is sufficient.
Practical usage suggestions
- Interactive input : Use
fmt.Scanorfmt.Scanfto quickly get simple values. - Line input or pipeline processing : Use
bufio.Scannerfirst. - Large chunks of data or file streams : use
io.ReadAll(os.Stdin). - Remember to deal with
scanner.Err()anderrorto avoid silence failure.
Basically these common ways. Go's standard library is simple and efficient, and can easily handle most input scenarios with os.Stdin .
The above is the detailed content of reading from stdin in go by example. For more information, please follow other related articles on the PHP Chinese website!
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