C Programming printf() Function

Syntax

Key Points

• Prints ControlString to Standard Output (the terminal on a PC, typically a Universal Asynchronous Receiver Transmitter (UART) on microcontrollers)
• The MPLAB^® X IDE Simulator uses the UART1 Output window to display text written to the UART using printf()
• All comma-separated parameters are optional except for ControlString
• The argument parameters (arg1, …, argN above) can be variables or other data to be embedded within ControlString
• Placeholders are put in ControlString to indicate where the value of an argument parameter should be inserted
• Placeholders indicate the position in string and format to be used in printing data embedded within ControlString
• printf() requires a huge amount of memory. Best used for debugging only unless you need all of its functionality

The code above would produce the following output:

Where "_" indicates the position of the cursor at the end of the operation.

• The code in Example 1 defines two variables: a and b
• We want to print their values as part of a string that indicates which value goes with which variable
• The ControlString is "a = %d\nb = %d\n"
• Each %d is a placeholder that indicates where one of the arguments should be inserted and how it should be formatted when printed
• The value of a is inserted at the position of the first %d and the value of b is inserted at the position of the second %d
• The d in the %d is called a format specifier or a conversion character and indicates that the value should be printed as a signed decimal integer
• The \n is an escape sequence indicating that a new line should be inserted, causing the cursor to go down to the next line before continuing to print

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Format Specifiers

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