How to Use cat in R: Syntax, Examples, and Tips

In R, cat() is used to print text and variables to the console without quotes and with control over spacing and line breaks. You pass strings or variables separated by commas, and use \n for new lines inside the text.

Syntax

The basic syntax of cat() is:

• cat(..., file = "", sep = " ", fill = FALSE, labels = NULL, append = FALSE)

Where:

• ... are the objects (text or variables) to print.
• file specifies a file to write to instead of the console.
• sep is the separator between objects (default is a space).
• fill controls line wrapping.
• labels is deprecated and ignored.
• append decides if output appends to a file.

r

cat(..., file = "", sep = " ", fill = FALSE, labels = NULL, append = FALSE)

Example

This example shows how to print text and variables together using cat(). It also demonstrates adding a new line with \n.

r

name <- "Alice"
age <- 30
cat("Name:", name, "\nAge:", age, "years\n")

Output

Name: Alice 
Age: 30 years

Common Pitfalls

One common mistake is expecting cat() to add a new line automatically like print(). You must add \n explicitly for line breaks. Another is forgetting that cat() does not show quotes around strings, which can confuse beginners.

r

cat("Hello")
cat("World")

# Correct way with new line
cat("Hello\n")
cat("World\n")

Output

HelloWorld
Hello
World

Quick Reference

Use cat() to print combined text and variables without quotes. Remember to add \n for new lines. Use sep to change space between items.

Parameter	Description	Default
...	Objects to print (text or variables)	Required
file	File to write output (empty means console)	""
sep	Separator between objects	" "
fill	Line wrap control	FALSE
labels	Deprecated and ignored	NULL
append	Append to file if TRUE	FALSE

Key Takeaways

Use cat() to print text and variables together without quotes in R.

Add \n inside strings to create new lines when using cat().

cat() does not add spaces or new lines automatically; control them with sep and \n.

cat() can write output to files using the file parameter.

Remember cat() outputs directly and returns NULL invisibly.