Instr

Syntax:

    location = Instr(source, find)

Command Availability:

Available on all microcontrollers.

Explanation:

The Instr function searches one string to find the location of another string within it. source is the string to search inside, and find is the string to find. The function returns the location of find within source, or 0 if source does not contain find.

Example:

    'Set chip model
    #chip 16F1936

    'Set up hardware serial connection
    #define USART_BAUD_RATE 9600
    #define USART_TX_BLOCKING


    'Fill a string with a message
    Dim TestData As String
    TestData = "Hello, world!"

    'Display the location of "world" within the string
    'Will return 8, because "w" in world is the 8th character
    'of "Hello, world!"
    HSerPrint Instr(TestData, "world")          ' <<< the Instr instruction, a match found
    HSerPrintCRLF

    'Display the location of "planet" within the string
    'Will display 0, because "planet" does not occur inside
    'the string "Hello, world!"
    HSerPrint Instr(TestData, "planet")          ' <<< the Instr instruction, no match found
    HSerPrintCRLF

Key line: Instr(TestData, "world") — returns 8, the 1-based position where "world" begins inside TestData; the second call shows the not-found case, which returns 0 rather than an error.

See Also:

  • Mid — extracting the substring once its position is known
  • Asc — related command in the same category
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