🧵 Go String Interpolation – Complete Guide (2025 Edition)

Learn how to insert variables into strings in Go (Golang) using powerful formatting techniques.

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🚀 Introduction – What Is String Interpolation in Go?

String Interpolation refers to the process of inserting variables or expressions directly into a string. While Go does not support string interpolation in the traditional sense (like JavaScript or Python), it offers powerful alternatives using fmt package functions such as:

• fmt.Sprintf()
• fmt.Printf()

✅ These methods allow you to format strings dynamically by combining variables and text.

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📌 Go String Interpolation Using fmt.Sprintf()

✅ Basic Syntax

import "fmt"

name := "Vaibhav"
message := fmt.Sprintf("Hello, %s!", name)
fmt.Println(message) // Output: Hello, Vaibhav!

🔹 Format Specifiers:

Specifier	Description
%s	String
%d	Decimal (int)
%f	Float
%t	Boolean
%v	Any value (default)

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🔍 Examples of Go String Interpolation

🔹 Interpolating Multiple Variables

age := 30
name := "Vaibhav"
msg := fmt.Sprintf("%s is %d years old.", name, age)
fmt.Println(msg) // Output: Vaibhav is 30 years old.

🔹 Formatting Numbers

price := 49.99
result := fmt.Sprintf("The price is $%.2f", price)
fmt.Println(result) // Output: The price is $49.99

🔹 Using %v for Generic Formatting

x := true
fmt.Printf("Value: %v\n", x) // Output: Value: true

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🧩 Alternative: fmt.Printf() for Direct Output

Instead of returning a string, fmt.Printf() prints it directly to the console.

name := "GoLang"
fmt.Printf("Welcome to %s programming!\n", name)

📌 Use Printf() for formatted printing, and Sprintf() for formatted string generation.

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🧠 Advanced String Formatting

🔹 Padding and Alignment

fmt.Printf("|%-10s|%10s|\n", "Left", "Right")

🔹 Data Structure Formatting

user := struct {
    Name string
    Age  int
}{"Alex", 28}

fmt.Printf("User Info: %+v\n", user)

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✅ Use Cases of String Interpolation in Go

Use Case	Example
Console Logging	fmt.Printf() for readable output
Dynamic HTML templates	Insert data into HTML templates
API Message Formatting	Create readable JSON or error logs
File and Report Writing	fmt.Sprintf() to format content

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🧾 Summary

Although Go doesn’t support direct string interpolation like some other languages, it provides powerful formatting tools using the fmt package:

• fmt.Sprintf() – returns a formatted string
• fmt.Printf() – prints a formatted string
• Format specifiers let you control output precisely

💡 Tip: Use %v for general formatting, and %+v or %#v for struct introspection in debugging.

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❓ Frequently Asked Questions (FAQ)

🔹 Q1. Does Go support native string interpolation?

A: No. Go does not support native interpolation like "Hello, ${name}". Use fmt.Sprintf() instead.

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🔹 Q2. What is the difference between Sprintf and Printf?

A: Sprintf returns the formatted string; Printf prints it directly to the standard output.

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🔹 Q3. Can I use template literals like in JavaScript?

A: No. Go doesn’t support template literals. You must use format strings and fmt.Sprintf().

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🔹 Q4. How do I insert variables in a string in Go?

A: Use format specifiers like %s, %d, %f with fmt.Sprintf() to insert string, integer, or float variables.

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🔹 Q5. Is string concatenation better than interpolation?

A: For simple strings, + can be faster. For complex or structured formatting, fmt.Sprintf() is preferred for readability and maintainability.

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