How to Trim Whitespace from a String in Go

Use the strings.TrimSpace() function to remove leading and trailing whitespace, or strings.Trim() with a custom cutset for specific characters. These functions are part of the standard strings package and return a new string without modifying the original.

Here is the standard approach for removing common whitespace characters (spaces, tabs, newlines, carriage returns):

package main

import (
	"fmt"
	"strings"
)

func main() {
	input := "   hello world   \n"
	
	// Removes leading and trailing whitespace
	cleaned := strings.TrimSpace(input)
	
	fmt.Printf("Original: %q\n", input)
	fmt.Printf("Trimmed:  %q\n", cleaned)
	
	// Output:
	// Original: "   hello world   \n"
	// Trimmed:  "hello world"
}

If you need to remove only specific characters (e.g., spaces but not newlines) or trim from just one side, use strings.Trim(), strings.TrimLeft(), or strings.TrimRight(). These accept a cutset string containing every character you want to remove.

package main

import (
	"fmt"
	"strings"
)

func main() {
	input := "###hello###"
	
	// Removes '#' from both ends
	cleaned := strings.Trim(input, "#")
	
	// Removes only leading spaces
	leftTrimmed := strings.TrimLeft("   test", " ")
	
	// Removes only trailing newlines
	rightTrimmed := strings.TrimRight("test\n\n", "\n")
	
	fmt.Printf("%q\n", cleaned)      // "hello"
	fmt.Printf("%q\n", leftTrimmed)  // "test"
	fmt.Printf("%q\n", rightTrimmed) // "test"
}

Note that TrimSpace is generally preferred for user input or log parsing because it handles all Unicode whitespace characters defined by the Unicode standard, whereas Trim with a manual cutset only removes the exact characters you specify. If you need to trim whitespace from the middle of a string, these functions won't work; you would need to split the string by whitespace and join it back together using strings.Join(strings.Fields(input), " ").

Trimming whitespace from a string in Go removes empty spaces from the start and end of a text string. It is useful for cleaning up user input or data read from files before processing. Think of it as trimming the edges off a piece of paper so only the content remains.