Golang : Characters limiter example



Tags : golang character-limiter io-readatleast

Problem:

You want to limit a string to X number of characters. How to do that?

Solution:

Use io.ReadAtLeast() function to read from the string but limited to the X number of characters.

For example:

 package main

 import (
 "fmt"
 "io"
 "strings"
 )

 // Limits a string to X number of characters.

 func char_limiter(s string, limit int) string {

 reader := strings.NewReader(s)

 // create buffer with specified limit of chraracters
 buff := make([]byte, limit)

 n, _ := io.ReadAtLeast(reader, buff, limit)

 if n != 0 {
 //fmt.Printf("\n %s ", buff)
 return string(buff) + "..."
 } else {
 // nothing happens, return original string
 return s
 }

 }

 func main() {

 str := "ReadAtLeast reads from r into buf until it has read at least min bytes. It returns the number of bytes copied and an error if fewer bytes were read. The error is EOF only if no bytes were read. If an EOF happens after reading fewer than min bytes, ReadAtLeast returns ErrUnexpectedEOF. If min is greater than the length of buf, ReadAtLeast returns ErrShortBuffer. On return, n >= min if and only if err == nil."

 fmt.Printf("Original : [%s] \n", str)

 // limit to 10 characters
 fmt.Println("10 characters : ", char_limiter(str, 10))

 // limit to 30 characters
 fmt.Println("30 characters : ", char_limiter(str, 30))

 // limit to 100 characters
 fmt.Println("100 characters : ", char_limiter(str, 100))

 }

Output:

Original : [ReadAtLeast reads from r into buf until it has read at least min bytes. It returns the number of bytes copied and an error if fewer bytes were read. The error is EOF only if no bytes were read. If an EOF happens after reading fewer than min bytes, ReadAtLeast returns ErrUnexpectedEOF. If min is greater than the length of buf, ReadAtLeast returns ErrShortBuffer. On return, n >= min if and only if err == nil.]

10 characters : ReadAtLeas...

30 characters : ReadAtLeast reads from r into ...

100 characters : ReadAtLeast reads from r into buf until it has read at least min bytes. It returns the number of byt...

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  See also : Golang : Word limiter example



Tags : golang character-limiter io-readatleast

By Adam Ng

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