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Swift Comments

A comment is a note written in code for people to read. The program ignores every comment.

A comment on its own line

The note above the print explains that line. Only the greeting reaches the screen.

// Print a greeting
print("Hello")

A comment after code

The note after the code explains that print line. The printed words are the only output.

print("Hello again") // Print another greeting

A block comment

The block note spans two lines above the prints. Both printed words still appear in order.

/*
Print two short lines
Each line shows one word
*/
print("First")
print("Second")

Example

// Print the title
print("Morning")
/* Print the next line
The step prints below this note */
print("Tea")

Key points

  • Use // to start a line comment.
  • A line comment runs to the end of its line.
  • Use /* to open a block comment and */ to close it.
  • A comment can sit above a line of code or after code on the same line.

In this example, a line comment sits above the first print, and that print shows Morning. A block comment sits above the second print, and that print shows Tea.

Try it Yourself

Edit the code, then press Run.

Running is simulated

Exercise

What does a program do with a comment?