string.format()
The string.format() function creates a formatted string using a format string and optional arguments. It is useful for formatting numbers, strings, and other values in a structured way.
Syntax
string.format(formatString, ...)
Parameters
- Name
formatString- Type
- string
- Description
A string specifying the desired format. It can include format specifiers for values to insert.
- Name
...- Type
- varargs
- Description
A variable number of arguments to format and insert into the
formatString.
Return Value
Returns the formatted string after applying the format specifiers.
Common Format Specifiers
| Specifier | Description |
|---|---|
%d | Formats a number as an integer. |
%f | Formats a number as a floating-point value. |
%s | Inserts a string. |
%x/%X | Formats a number as a hexadecimal (lower/uppercase). |
%e/%E | Formats a number in scientific notation. |
%% | Inserts a literal % character. |
Examples
Example 1: Basic Formatting
Format a string with a number and a word.
Example 1
local formatted = string.format("I have %d apples and %s oranges.", 5, "seven")
print(formatted)
-- Output: I have 5 apples and seven oranges.
Example 2: Floating-point Formatting
Control the number of decimal places for a float.
Example 2
local pi = math.pi
local formatted = string.format("Value of pi: %.2f", pi)
print(formatted)
-- Output: Value of pi: 3.14
Example 3: Hexadecimal Formatting
Convert numbers to hexadecimal.
Example 3
local number = 255
local formatted = string.format("Hexadecimal: %x", number)
print(formatted)
-- Output: Hexadecimal: ff
Example 4: Scientific Notation
Format numbers in scientific notation.
Example 4
local number = 123456789
local formatted = string.format("Scientific: %e", number)
print(formatted)
-- Output: Scientific: 1.234568e+08
Example 5: Literal Percent Sign
Include a % character in the output.
Example 5
local formatted = string.format("Progress: %d%% complete", 75)
print(formatted)
-- Output: Progress: 75% complete
Use Cases
- Dynamic Strings: Insert variables into a string in a structured way.
- Formatting Numbers: Control how numbers are displayed, including decimals or scientific notation.
- Hexadecimal Conversion: Represent numbers in base-16 for specific applications.
- Data Reports: Create neatly formatted output for tables or logs.
See also
string.gsub(): Replace substrings in a string, often used in conjunction withstring.format()for dynamic replacements.string.rep(): Repeat a string multiple times, useful for formatting or padding.string.sub(): Extract substrings, which can be helpful for dynamic formatting.