Golang strconv.QuoteToASCII

last modified April 20, 2025

This tutorial explains how to use the strconv.QuoteToASCII function in Go. We'll cover string quoting basics with practical examples.

The strconv.QuoteToASCII function converts a string to an ASCII-only quoted string. Non-ASCII characters are escaped using Go escape sequences.

This function is useful when you need to represent strings in ASCII-only environments or when you want to safely display non-printable characters.

Basic strconv.QuoteToASCII Example

The simplest use of strconv.QuoteToASCII converts a string to its ASCII-quoted representation. Here we demonstrate basic usage.

basic_quote.go

package main

import (
    "fmt"
    "strconv"
)

func main() {
    str := "Hello, 世界"
    
    quoted := strconv.QuoteToASCII(str)
    fmt.Printf("Original: %s\nQuoted: %s\n", str, quoted)
}

We convert a string containing non-ASCII characters to an ASCII-quoted string. The output shows how Unicode characters are escaped in the quoted version.

Quoting Special Characters

strconv.QuoteToASCII handles special characters like newlines and tabs. This example shows how they're represented in the output.

special_chars.go

package main

import (
    "fmt"
    "strconv"
)

func main() {
    str := "Line1\nLine2\tTab"
    
    quoted := strconv.QuoteToASCII(str)
    fmt.Printf("Original: %s\nQuoted: %s\n", str, quoted)
}

Special characters like newline and tab are escaped in the quoted output. This makes the string representation safe for ASCII-only environments.

Quoting Empty String

The function handles edge cases like empty strings consistently. This example shows the behavior with empty and whitespace-only strings.

empty_string.go

package main

import (
    "fmt"
    "strconv"
)

func main() {
    empty := ""
    space := "   "
    
    fmt.Println("Empty:", strconv.QuoteToASCII(empty))
    fmt.Println("Spaces:", strconv.QuoteToASCII(space))
}

An empty string is quoted as two double quotes. Whitespace characters are preserved but quoted like any other characters.

Comparing Quote and QuoteToASCII

This example compares QuoteToASCII with the regular Quote function to highlight their differences.

compare_quote.go

package main

import (
    "fmt"
    "strconv"
)

func main() {
    str := "Hello, 世界"
    
    fmt.Println("Quote:", strconv.Quote(str))
    fmt.Println("QuoteToASCII:", strconv.QuoteToASCII(str))
}

Quote preserves Unicode characters while QuoteToASCII escapes them. Use QuoteToASCII when ASCII output is required.

Quoting Control Characters

Control characters are properly escaped by QuoteToASCII. This example demonstrates how they're represented.

control_chars.go

package main

import (
    "fmt"
    "strconv"
)

func main() {
    str := string([]byte{0, 1, 2, 31, 127})
    
    quoted := strconv.QuoteToASCII(str)
    fmt.Printf("Original: %q\nQuoted: %s\n", str, quoted)
}

Non-printable control characters are escaped using hexadecimal notation. This makes them visible and safe for ASCII output.

Quoting Strings for JSON

QuoteToASCII can be used to prepare strings for JSON output. This example shows how it escapes special JSON characters.

json_quoting.go

package main

import (
    "fmt"
    "strconv"
)

func main() {
    str := `{"name": "John", "age": 30}`
    
    quoted := strconv.QuoteToASCII(str)
    fmt.Println("Quoted JSON:", quoted)
}

The function properly escapes quotes and other special characters that might appear in JSON strings. This helps prevent JSON parsing errors.

Practical Example: Logging Non-ASCII Data

This practical example demonstrates using QuoteToASCII to safely log strings that might contain non-ASCII characters.

logging.go

package main

import (
    "fmt"
    "strconv"
)

func logSafe(message string) {
    safeMsg := strconv.QuoteToASCII(message)
    fmt.Println("LOG:", safeMsg)
}

func main() {
    logSafe("Normal message")
    logSafe("Message with Unicode: 日本語")
    logSafe("Message with control chars: \x00\x1F")
}

The logSafe function ensures all logged messages are ASCII-safe. This prevents encoding issues in systems that expect ASCII-only input.

Source

Go strconv package documentation

This tutorial covered the strconv.QuoteToASCII function in Go with practical examples of string quoting in various scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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