March 21, 2018, 11:10:52 PM
Welcome,
Guest
. Please
login
or
register
.
Did you miss your
activation email?
1 Hour
1 Day
1 Week
1 Month
Forever
Login with username, password and session length
Read this please.
♦
The Great Kangaroo Escape
♦
Looking for reviews of the 4th ed on Amazon!
♦
Twitter:
@skochan
Home
Help
Search
Login
Register
Chat
Official Forum for Programming in Objective-C (the iPhone Programming Language) - Stephen Kochan
>
Old Stuff
>
Chapter Study
>
Chapter 12 - The Preprocessor
>
P252
Pages: [
1
]
Go Down
« previous
next »
Print
Author
Topic: P252 (Read 1418 times)
bamboo
Newbie
Posts: 14
P252
«
on:
April 17, 2011, 11:29:21 AM »
"As an example of how this can be used, the following lines appear in the Foundation header file NSString.h:
#if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_5
#define NSMaximumStringLength (INT_MAX-1)
#endif
This tests the value of the defined variable MAC_OS_X_VERSION_MIN_REQUIRED against the defined variable MAC_OS_X_VERSION_10_5. If the former is less than the latter, the #define that follows is processed; otherwise, it is skipped. "
I am reading Chapter 12 The Preprocessor today, and this sentence confuses me.
from the name MAC_OS_X_VERSION_MIN_REQUIRED, it seems like it is defined name using the #define statement, but since a defined name is not a variable, as it's mentioned previously.
can someone tell me what kind data type it is?
Logged
skochan
Administrator
Hero Member
Posts: 3114
Re: P252
«
Reply #1 on:
September 09, 2011, 03:03:20 PM »
They are defined names and their values get substituted and then compared by the #if, which can evaluate numeric expressions. So there's a double processing (in a sense) of that line that's done by the preprocessor: first substitute the text defined for the two name, then evaluate the expression.
Cheers,
Steve
Logged
Pages: [
1
]
Go Up
Print
« previous
next »
Jump to:
Please select a destination:
-----------------------------
Programming in Objective-C, 5th edition
-----------------------------
=> General Discussions
=> Exercises
-----------------------------
Programming in Objective-C, 4th edition
-----------------------------
=> General Discussion
=> Exercises
===> Chapter 2
===> Chapter 3
===> Chapter 4
===> Chapter 5
===> Chapter 6
===> Chapter 7
===> Chapter 8
===> Chapter 9
===> Chapter 10
===> Chapter 11
===> Chapter 12
===> Chapter 13
===> Chapter 14
===> Chapter 15
===> Chapter 16
===> Chapter 17
===> Chapter 18
===> Chapter 19
===> Chapter 20
===> Chapter 21
=> Chapter 2
=> Chapter 3
=> Chapter 4
=> Chapter 5
=> Chapter 6
=> Chapter 7
=> Chapter 8
=> Chapter 9
=> Chapter 10
=> Chapter 11
=> Chapter 12
=> Chapter 13
=> Chapter 14
=> Chapter 15
=> Chapter 16
=> Chapter 17
=> Chapter 18
=> Chapter 19
=> Chapter 20
=> Chapter 21
=> Errata
===> 1st Printing
===> 2nd Printing
-----------------------------
Members' Corner
-----------------------------
=> Look What I'm Doing...
-----------------------------
Study Group
-----------------------------
=> Objective-C Quizzes
===> Comprehensive Quiz
===> Chapter 1 - Introduction
===> Chapter 2 - Programming in Objective-C
===> Chapter 3 - Classes, Objects, and Methods
===> Chapter 4 - Data Types and Expressions
===> Chapter 5 - Program Looping
===> Chapter 6 - Making Decisions
===> Chapter 7 - More on Classes
===> Chapter 8 - Inheritance
===> Chapter 9 - Polymorphism, Dynamic Typing, and Dynamic Binding
===> Chapter 10 - More on Variables and Data Types
===> Chapter 11 - Categories and Protocols
===> Chapter 12 - The Preprocessor
===> Chapter 15 - Numbers, Strings & Collections
===> Chapter 17 - Memory Management
-----------------------------
iOS Programming
-----------------------------
=> General Questions
-----------------------------
Programming in C, 3rd ed. (Stephen Kochan)
-----------------------------
=> Programming in C webcasts?
=> Answers to Odd-Numbered Exercises
=> Questions and Help
-----------------------------
Old Stuff
-----------------------------
=> Errata, Answers to Exercises, Code, etc.
=> Shared Code Library
=> Welcome
=> News
=> Errata
===> 1st Printing
===> 2nd printing
=> Newbie Corner
=> Chapter Study
===> Chapter 2 - Programming in Objective-C
===> Chapter 3 - Classes, Objects, and Methods
===> Chapter 4 - Data Types and Expressions
===> Chapter 5 - Program Looping
===> Chapter 6 - Making Decisions
===> Chapter 7 - More on Classes
===> Chapter 8 - Inheritance
===> Chapter 9 - Polymorphism, Dynamic Typing, and Dynamic Binding
===> Chapter 10 - More on Variables and Data Types
===> Chapter 11 - Categories and Protocols
===> Chapter 12 - The Preprocessor
===> Chapter 13 - Underlying C Language Features
===> Chapter 15 - Numbers, Strings, and Collections
===> Chapter 16 - Working with Files
===> Chapter 17 - Memory Management
===> Chapter 18 - Copying Objects
===> Chapter 19 - Archiving
===> Chapter 21 - Writing iPhone Applications
=> Answers to Exercises
===> Chapter 2
===> Chapter 3
===> Chapter 4
===> Chapter 5
===> Chapter 6
===> Chapter 7
===> Chapter 8
===> Chapter 9
===> Chapter 10
===> Chapter 11
===> Chapter 12
===> Chapter 13
===> Chapter 15
===> Chapter 16
===> Chapter 17
===> Chapter 18
===> Chapter 19
===> Chapter 21
=> General Discussion
=> Program Examples
===> Chapter 2
===> Chapter 3
===> Chapter 4
===> Chapter 5
===> Chapter 6
===> Chapter 7
===> Chapter 8
===> Chapter 9
===> Chapter 10
===> Chapter 11
===> Chapter 12
===> Chapter 13
===> Chapter 15
===> Chapter 16
===> Chapter 17
===> Chapter 18
===> Chapter 19
===> Chapter 21
=> XCode 4 Help
=> Suggestions
=> Help!!!
=> Fraction Calculator Available from the App Store
=> Resources
=> Errata
===> 1st & 2nd printings
===> 3rd & 4th printings
===> 5th printing
===> Current Errata
=> Suggestion Box
=> Tips & Tricks
=> Part 3
===> Welcome to the Class
===> Special Announcements
===> Assignments
=> Parts 1 and 2
===> Welcome to the Class
===> Questions and Discussion
===> SPECIAL ANNOUNCEMENTS
===> Assignments
===> Chapter 4, Exercise 7
===> Suggestions
=> Webcast Series Part I, Sept. 1 - 24
===> Welcome
===> SPECIAL ANNOUNCEMENTS
===> Questions and Discussion
===> Assignments
===> Chapter 4, Exercise 7
===> Chapter 6, Exercise 4
===> Suggestions
=> Webcast Series Part II, Oct. 1 - 27
===> Welcome
===> SPECIAL ANNOUNCEMENTS
===> Questions and Discussion
===> Assignments
===> Example using hasPrefix: and hasSufix:
===> Suggestions
=> Objective-C Workshop Aug 11 - 13
=> Webcast Series Part I, Oct. 29 - Dec. 1
===> Welcome
===> SPECIAL ANNOUNCEMENTS
===> Assignments
===> Chapter 4, Exercise 7
===> Chapter 6, Exercise 4
===> Suggestions
=> Webcast Series Part II, Jan 5 - 28
===> Welcome
===> SPECIAL ANNOUNCEMENTS
===> Assignments
===> Jan 7th Solutions
Loading...