Single Lines In C Comments

Discussion in 'Mac Programming' started by Marjamrob1, Jan 29, 2013.

  1. macrumors regular

    Joined:
    Jul 19, 2012
    #1
    When reading an older development book, I found this:

    However I have written C programs, that use "//" single line comments.
     
  2. ytk
    macrumors regular

    Joined:
    Jul 8, 2010
    #2
    Originally, the only style for commenting in C was /* ... */. This is still the case in C89, which is traditionally known as ANSI-C. C99 added support for one line comments using //. If your book was written before the C99 standard was approved, it was correct at the time, and still is for older systems.
     
  3. thread starter macrumors regular

    Joined:
    Jul 19, 2012
    #3
    Ok, thank you, I understand now. I haven't actually ever used anything besides C99
     
  4. macrumors 6502

    Madd the Sane

    Joined:
    Nov 8, 2010
    Location:
    Utah
  5. thread starter macrumors regular

    Joined:
    Jul 19, 2012
    #5
    C++ when it was invented in 78 at Bell, or C++98
     
  6. macrumors 603

    Joined:
    Aug 9, 2009
    #6
    Why does it matter?


    There was a period of time when the C compilers used by Apple accepted // comments even though it wasn't in the ANSI/ISO C standard of the time. There was a command-line option for strict C conformance that would turn this off, so // was forbidden. IIRC, there was another option that would force strict compliance to the ISO C standard, EXCEPT that // comments were allowed. Other than as a historical footnote, none of this matters today, and hasn't since C99.
     
  7. macrumors 6502

    ElectricSheep

    Joined:
    Feb 18, 2004
    Location:
    Wilmington, DE
    #7
    They originally came from BCPL, which was also the first brace programming language. But, this is just esoteric trivia.
     
  8. thread starter macrumors regular

    Joined:
    Jul 19, 2012
    #8
    I was just curious but thank you.
     

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