String concatenation and << in Ruby

Introduction

We join pieces of text together to make longer messages or combine words. This helps us build sentences or data step by step.

When you want to add a greeting and a name to make a full message.

When you read parts of a sentence from different places and want to join them.

When you build a list of words or phrases into one string.

When you want to add more text to an existing message without creating a new one.

Syntax

Ruby

string1 + string2
string1 << string2

The + operator creates a new string by joining two strings.

The << operator adds the second string to the first one directly, changing the original string.

Examples

This uses + to join two strings into a new one.

Ruby

greeting = "Hello, " + "world!"
puts greeting

This uses << to add text to the existing string.

Ruby

greeting = "Hello, "
greeting << "world!"
puts greeting

Combines a variable and strings using +.

Ruby

name = "Alice"
message = "Hi " + name + "!"
puts message

Sample Program

This program first adds " morning" to "Good" using <<, then adds "!" using +. Finally, it prints the full message.

Ruby

message = "Good"
message << " morning"
message = message + "!"
puts message

Important Notes

Using + creates a new string and does not change the original string.

Using << changes the original string by adding more text to it.

For many additions, << is faster and uses less memory.

Summary

+ joins strings but makes a new one.

<< adds text to the existing string.

Use << when you want to build a string step by step.