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1. Top results related to what is the difference between objective c and objective c + +?

   • What is the difference between #import and #include in Objective-C?

     Top Answer

     Answered Sep 27, 2014 · 360 votes

     The #import directive was added to Objective-C as an improved version of #include. Whether or not it's improved, however, is still a matter of debate. #import ensures that a file is only ever included once so that you never have a problem with recursive includes. However, most decent header files protect themselves against this anyway, so it's not really that much of a benefit.

     Basically, it's up to you to decide which you want to use. I tend to #import headers for Objective-C things (like class definitions and such) and #include standard C stuff that I need. For example, one of my source files might look like this:

     #import <Foundation/Foundation.h>-#include <asl.h>#include <mach/mach.h>-

     Other Answers

     Answered Sep 17, 2010 · 387 votes

     There seems to be a lot of confusion regarding the preprocessor.

     What the compiler does when it sees a #include that it replaces that line with the contents of the included files, no questions asked.

     So if you have a file a.h with this contents:

     typedef int my_number;-

     and a file b.c with this content:

     #include "a.h"#include "a.h"-

     the file b.c will be translated by the preprocessor before compilation to

     typedef int my_number;typedef int my_number;-

     which will result in a compiler error, since the type my_number is defined twice. Even though the definition is the same this is not allowed by the C language.

     Since a header often is used in more than one place include guards usually are used in C. This looks like this:

     #ifndef _a_h_included_ #define _a_h_included_- typedef int my_number;- #endif-

     The file b.c still would have the whole contents of the header in it twice after being preprocessed. But the second instance would be ignored since the macro _a_h_included_ would already have been defined.

     This works really well, but has two drawbacks. First of all the include guards have to be written, and the macro name has to be different in every header. And secondly the compiler has still to look for the header file and read it as often as it is included.

     Objective-C has the #import preprocessor instruction (it also can be used for C and C++ code with some compilers and options). This does almost the same as #include, but it also notes internally which file has already been included. The #import line is only replaced by the contents of the named file for the first time it is encountered. Every time after that it is just ignored.

     Other Answers

     Answered Jul 11, 2013 · 70 votes

     I agree with Jason.

     I got caught out doing this:

     #import <sys/time.h> // to use gettimeofday() function#import <time.h> // to use time() function-

     For GNU gcc, it kept complaining that time() function was not defined.

     So then I changed #import to #include and all went ok.

     Reason:

     You #import <sys/time.h>:     <sys/time.h> includes only a part of <time.h> by using #defines

     You #import <time.h>:     No go. Even though only part of <time.h> was already included, as     far as #import is concerned, that file is now already completely included.

     Bottom line:

     C/C++ headers traditionally includes parts of other include files. So for C/C++ headers, use #include. For objc/objc++ headers, use #import.

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     1/5

   • What is the difference between ivars and properties in Objective-C

     Top Answer

     Answered Aug 25, 2017 · 57 votes

     Number 1 differs from the other two by forward declaring the MyOtherObject class to minimize the amount of code seen by the compiler and linker and also potentially avoid circular references. If you do it this way remember to put the #import into the .m file.

     By declaring an @property, (and matching @synthesize in the .m) file, you auto-generate accessor methods with the memory semantics handled how you specify. The rule of thumb for most objects is Retain, but NSStrings, for instance should use Copy. Whereas Singletons and Delegates should usually use Assign. Hand-writing accessors is tedious and error-prone so this saves a lot of typing and dumb bugs.

     Also, declaring a synthesized property lets you call an accessor method using dot notation like this:

     self.otherObj = someOtherNewObject; // set it MyOtherObject *thingee = self.otherObj; // get it -

     Instead of the normal, message-passing way:

     [self setOtherObject:someOtherNewObject]; // set itMyOtherObject *thingee = [self otherObj]; // get it -

     Behind the scenes you're really calling a method that looks like this:

     - (void) setOtherObj:(MyOtherObject *)anOtherObject {- if (otherObject == anOtherObject) { return; }- MyOtherObject *oldOtherObject = otherObject; // keep a reference to the old value for a second otherObject = [anOtherObject retain]; // put the new value in [oldOtherObject release]; // let go of the old object} // set it-

     …or this

     - (MyOtherObject *) otherObject { return otherObject;} // get it-

     Total pain in the butt, right. Now do that for every ivar in the class. If you don't do it exactly right, you get a memory leak. Best to just let the compiler do the work.

     I see that Number 1 doesn't have an ivar. Assuming that's not a typo, it's fine because the @property / @synthesize directives will declare an ivar for you as well, behind the scenes. I believe this is new for Mac OS X - Snow Leopard and iOS4.

     Number 3 does not have those accessors generated so you have to write them yourself. If you want your accessor methods to have side effects, you do your standard memory management dance, as shown above, then do whatever side work you need to, inside the accessor method. If you synthesize a property as well as write your own, then your version has priority.

     Did I cover everything?

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     2/5

   • What is the difference between an instance variable/method and a class variable/method in Objective-C?

     Top Answer

     Answered Aug 07, 2010 · 2 votes

     An instance method or variable applies to that instance. A class method (classes in Objective-C don't have variables, though they can be simulated in various ways) applies to the whole class.

     Consider the quintessential Dog class, which derives from the Mammal class (and so on up the tree of life.) A particular dog has a name and a collar and an owner--those are its properties. A particular dog may -bark or -chaseBall or -buryBoneInBackyard--those are its methods.

     The Dog class, on the other hand, has different methods. The Dog class has a +globalPopulation and may instantiate itself with a +dogWithDNA: factory method. The Dog class will have an +isExtinct method indicating whether the species as a whole is extinct (it's not, of course.)

     In short: class methods affect the entire class, while instance methods affect a particular instance of a class.

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     3/5

   • What's the difference between Objective-C and Cocoa?

     Top Answer

     Answered Jan 12, 2009 · 66 votes

     Objective-C is the language... it defines all the things like the keywords for defining objects, the syntax for messaging object, things like that.

     Cocoa is a development framework (it's actually an umbrella framework which combines three other frameworks, Foundation, AppKit and CoreData).

     These frameworks (Cocoa) define all the objects that are nice to use and interact with the operating system, as well as a number of functions. For example, Cocoa defines things like NSString and NSObject. Cocoa can currently be used with other language bindings, such as python or ruby, and used to be used with Java as well. So, if you were using Cocoa with Java, you would still get an NSString object, but you would call and use it from within a Java application.

     Without linking to one of the Cocoa frameworks, Objective-C comes with only a very basic Object class as a pre-defined root class.

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     4/5

   • Objective C, difference between n++ and ++n

     Top Answer

     Answered May 29, 2014 · 17 votes

     ++n; increments the value of n before the expression is evaluated.

     n++; increments the value of n after the expression is evaluated.

     So compare the results of this

     int n = 41;int o = ++n; //n = 42, o = 42-

     with the results of this:

     int n = 41;int o = n++; //n = 42, o = 41-

     In the case of loops:

     for (int i = 0; i < j; i++) {/*...*/}-

     however it doesn't make any difference, unless you had something like this:

     for (int i = 0; i < j; x = i++) {/*...*/}-

     or this:

     for (int i = 0; i < j; x = ++i) {/*...*/}-

     One could say:

     It doesn't matter whether to use n++ or ++n as long as no second (related) variable is modified (based on n) within the same expression.

     The same rules apply to --n; and n--;, obviously.

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     5/5

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2. People also ask

   What is the difference between C and Objective C?

   • The main difference in C and Objective C is that C is a procedure programming language which doesn’t support the concepts of objects and classes and Objective C is Object-oriented language which contains the concept of both procedural and object-oriented programming languages. Difference between C and Objective C:

   Difference between C and Objective C - GeeksforGeeks

   www.geeksforgeeks.org/difference-between-c-and-objective-c/

   See all results for this question

   Is Objective C a programming language?

   • Objective C is a general-purpose, object-oriented programming language that’s a superset of C. Objective C has been around since 1980 and became the main language for NeXTSTEP operating system. NeXTSTEP is the system from which Apple derived iOS and OS X. What Is Objective C Used For?

   What Is Objective C? (Definition, Uses, vs. Swift) | Built In

   builtin.com/software-engineering-perspectives/objective-c

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   Why is Objective-C better than C++?

   • Objective-C lacks the namespace feature of C++. Objective-C lacks an equivalent to C++ references. Objective-C lacks templates, preferring (for example) to instead allow weak typing in containers. Objective-C doesn't allow implicit method overloading, but C++ does.

   How different is Objective-C from C++? - Stack Overflow

   stackoverflow.com/questions/2445050/how-different-is-objective-c-from-c

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   What is the difference between Objective C++ and pure C++?

   • @rhino: Objective-C++ is simply Objective-C (and its frameworks) with C++ code. Pure C++ is not objective, it's object-oriented. @BoltClock: What is the difference between being objective and Object oriented? @Krishnan: I think the word objective here is just part of the name Objective-C and doesn't mean anything special itself.

   What is the difference between c++, objective-c and objective-c++

   stackoverflow.com/questions/3804219/what-is-the-difference-between-c-objective-c-and-objective-c

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3. www.codecademy.com › resources › blogHow Are C, C++, C#, and Objective-C Different? - Codecademy

   www.codecademy.com › resources › blog

   • Cached

   Mar 4, 2022 · What are the differences between C, C++, C#, and Objective-C? In this article, we'll look at the differences between these languages and what they're used for.

4. www.geeksforgeeks.org › difference-between-c-andDifference between C and Objective C - GeeksforGeeks

   www.geeksforgeeks.org › difference-between-c-and

   • Cached

   Dec 26, 2020 · The main difference in C and Objective C is that C is a procedure programming language which doesn’t support the concepts of objects and classes and Objective C is Object-oriented language which contains the concept of both procedural and object-oriented programming languages.

   C Language	Objective C
   It is a procedure oriented programming ...	Objective c is an object-oriented ...
   C language can be called the subset of ...	Objective C can be called the super set ...
   The pointers used in C language are ...	The language objective C uses null ...
   It is basically a low level language that ...	Objective C is a high-level language ...

   See full list on geeksforgeeks.org

5. stackoverflow.com › questions › 3804219What is the difference between c++, objective-c and objective ...

   stackoverflow.com › questions › 3804219

   • Cached

   Oct 14, 2010 · Feb 23, 2011 at 12:54. 1. @BoldClock: The difference is Objective-C is dynamically typed and C++ is statically typed. And Objective-C++ has it both.

   • C++ is Bjarne Stroustroup's language based on adding classes and metaprogramming to C in such a way that puts most additional work into the compile...
   • C++ and Objective C were/are two different approaches to adding object orientation to C. Current objective C compilers also accept C++ as input, so...
   • 1) C++ is a language derived from C that adds Object Orientation (OO) amongst other features. 2) Objective-C is a language derived from C that add...

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7. builtin.com › objective-cWhat Is Objective C? (Definition, Uses, vs. Swift) | Built In

   builtin.com › objective-c

   • Cached

   Dec 22, 2022 · Objective C vs. C: What’s the Difference? Syntactically speaking, Objective C is an extension of the popular C programming language. This means knowing C will definitely help you learn Objective C. One of the key differences between Objective C and C is that Objective C has an object-oriented class system not present in C.

8. www.geeksforgeeks.org › what-is-objective-cWhat Is Objective C? (Definition, Uses, vs. Swift ...

   www.geeksforgeeks.org › what-is-objective-c

   • Cached

   Mar 5, 2024 · Objective-C is a superset of the C programming language, which means Objective-C extends C with its object-oriented features. It combines the features and syntax of the C programming language with Smalltalk-style messaging objects.

9. www.designveloper.com › blog › what-is-objective-cWhat Is Objective-C: Definition, Usages & App Examples

   www.designveloper.com › blog › what-is-objective-c

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   Sep 17, 2022 · Let’s get into it. What Is Objective C? Objective C is a general-purpose programming language that is safe for different types of data, focuses on objects. It is also basically a superset of C. Its main purpose is to help make apps for operating systems like OS X and iOS. Apple has been using Objective C since buying NeXT in the late 1990s.

10. www.studytonight.com › difference-betweenDifference Between C and Objective C - Studytonight

    www.studytonight.com › difference-between

    • Cached

    Conclusion. C and Objective C are currently popular programming languages. Objective C is a superset of C that incorporates object-oriented programming and other capabilities. Objective C is a multi-paradigm programming language and a superset of C, while C is a structured programming language.