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1. Top results related to what is the difference between 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

   • C++ What is the difference between definition and instantiation?

     Top Answer

     Answered Oct 31, 2016 · 1 votes

     There are:

     1) variable definitions,

     2) variable/object instantiations, and

     3) template instantiations.

     1 & 3 are specific C++ terminology. 2 is more general terminology that might be used with C++. It is not an "officially" defined term for C++.

     I understand that your question is about 1 and 2, but not 3. 3 is different than 2, though related in meaning. I won't address 3 further as I don't believe it is part of your question.

     Instantiation is the creation of an object instance. It is more usual to use the term in reference to a class object than something like an int or double.

     A C++ variable definition does cause an object of the type being defined to be instantiated. It is, however, possible in C++ to instantiate an object other than via a variable definition.

     Example 1:

     std::string name;-

     The variable name, a std::string, is defined and (at run-time) instantiated.

     Example 2:

     std::string *namePointer;-

     The variable namePointer, a pointer, is defined and might be said (at run-time) to be instantiated (though not initialized). There is no std::string variable and no std::string is instantiated.

     //simple example, not what one should usually write in real codenamePointer = new std::string("Some Text");-

     No additional variable is defined. A std::string object is instantiated (at run-time) and the separate and pre-existing namePointer variable also has its value set.

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     3/5

   • C++: What is the difference between ostream and ostringstream?

     Top Answer

     Answered May 17, 2020 · 37 votes

     Put succinctly: ostringstream provides a streambuf, ostream

     requires the user to provide one.

     To understand the implications, it's necessary to understand a little how streams work, and I'm not sure that there's a good explanation of this on the Web. The basic abstraction of ostream is formatting textual output. You give it an int or a double (or a user defined type—more on that later), and it convert it into a stream of characters, of type char. What it does with that stream depends on the streambuf which is attached to it; this is an example of the strategy pattern, where streambuf is an abstract base class of the strategy[1]. The standard provides two implementations of streambuf, filebuf and stringbuf; in practice, in all but the most trivial applications, you'll probably have some that you implement yourself.

     When outputting, you always use ostream; it's the class over which the << operators are defined. You're formatting your data into a stream of characters, and you don't really care where the stream ends up.

     When creating an instance: if you create an ostream, you must provideit with a streambuf yourself. More often, you'll create anofstream or an ostringstream. These are both "convenience" classes,which derive from ostream, and provide a streambuf for it (filebuf

     and stringbuf, as it happens). Practically speaking, all they do is provide the necessary streambuf (which affects the constructor and the destructor, and not very much else); in the case of ofstream, there are also a few extra functions which forward to additional functions in the filebuf interface.

     It's usual (but by no means required) when you define your own streambuf to provide convenience overloads of ostream (and istream, if relevant), along the same lines as ofstream or ostringstream.

     By the same token, when creating an instance, it's usual to use one of the "convenience" derived classes, rather than to use ostream directly and provide your own streambuf.

     And if all of this seems complicated: the iostream classes use just about all of the facilities of C++ (virtual functions, templates and function overloading all play an important role). If you're just learning C++, don't worry too much about it: just use ofstream or ostringstream when you construct an instance, but pass around references to ostream. And as you learn about techniques like virtual functions, templates and operator overloading, return to the iostreams to understand the role they play in making code more flexible.

     [1] For various reasons, std::streambuf is not actually abstract. But the implementations of the virtual functions in it are useless; extraction always returns EOF, and insertion always fails.

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     4/5

   • C# What is the difference between static and constant?

     Top Answer

     Answered Dec 18, 2010 · 11 votes

     const is dealt with at compile time. Every reference to that constant is replaced by the constant value.

     static is very different. It is a variable which exists only once but belongs to all objects of that type. It can be edited unless marked as readonly (or given a getter but no setter). If it is marked as readonly then it is essentially a constant, but it is handled at runtime, not by the compiler.

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     5/5

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

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

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   Dec 26, 2020 · The language objective C uses null pointers and hence is type safe compared to C. It is basically a low level language that stands too close to assembly level language. Objective C is a high-level language stuffed with small talk messaging style together with C. C language doesn’t incorporate any classes.

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

   www.codecademy.com › resources › blog

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   • The Need For Different Programming Languages
   • What Is The C Programming Language?
   • What Is The C++ Programming Language?
   • What Is The Objective-C Programming Language?
   • What Is The C# Programming Language?
   • Learn More

   Why would someone go through the trouble of creating a new programming language based on another one instead of using the original? First, it makes the new language accessible to the existing language’s user base. Second, it saves developers time since the existing language’s core features don’t need to be recreated from scratch. Third, technology ...

   See full list on codecademy.com

   C is a general-purpose, procedural programming language that was first developed by Dennis Ritchie in 1972. Ritchie created this new programming language based on existing programming languages: ALGOL, BCP, and B. He took features that worked in those languages and combined them to create C. Up to that point, all operating systems were created in a...

   See full list on codecademy.com

   C++ is a general-purpose programming language created by Bjarne Stroustrup in 1985 to extend the C language. It has all of C’s low-level memory manipulation features but added the object-oriented programming paradigm. While the other members of the C family have replaced C in some applications, C++ is the most common replacement for C. In fact, it’...

   See full list on codecademy.com

   Objective-C is a programming language that was developed in 1984 by Brad Cox and Tom Love. They saw the need to add the object-oriented paradigm to the C programming language but used the Smalltalk language as their guide. This led to one of the major differences between this member of the C family and the others in this article. Most of the syntax...

   See full list on codecademy.com

   C#, like all the other children of the C programming language in this article, is an object-oriented, general-purpose language. Microsoft released C# in 2000, adopting features from Java along with C. Instead of being compiled to run on a specific operating system, C# was compiled to run using the .NET common language runtime, much like Java was co...

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   Now you can tell the differences between the programming languages in the C family. It’s a pretty diverse family, but all these languages owe their existence to C. C is still a popular language, especially with embedded systems and places where object-oriented programming isn’t needed. Try our Learn C courseif you’re interested in learning the basi...

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

   builtin.com › objective-c

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   Dec 22, 2022 · When it comes to usage, C is a general-purpose language for Unix systems. A typical use case for C is to build system applications and desktop apps. Objective C is also a general-purpose programming language with an object-oriented edge to it. The primary use case for Objective C is building iOS apps and macOS applications.

5. stackoverflow.com › questions › 2445050How different is Objective-C from C++? - Stack Overflow

   stackoverflow.com › questions › 2445050

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   196. Short list of some of the major differences: C++ allows multiple inheritance, Objective-C doesn't. Unlike C++, Objective-C allows method parameters to be named and the method signature includes only the names and types of the parameters and return type (see bbum's and Chuck's comments below). In comparison, a C++ member function signature ...

   • Short list of some of the major differences: C++ allows multiple inheritance, Objective-C doesn't. Unlike C++, Objective-C allows method paramete...
   • While they are both rooted in C, they are two completely different languages. A major difference is that Objective-C is focused on runtime-decisio...
   • Off the top of my head: Styles - Obj-C is dynamic, C++ is typically static. Although they are both OOP, I'm certain the solutions would be differ...
   • They're completely different. Objective C has more in common with Smalltalk than with C++ (well, except for the syntax, really).
   • As others have said, Objective-C is much more dynamic in terms of how it thinks of objects vs. C++'s fairly static realm. Objective-C, being in th...
   • Objective-C is a more perfect superset of C. In C and Objective-C implicit casting from void* to a struct pointer is allowed. Foo* bar = malloc(si...
   • Obj-C has much more dynamic capabilities in the language itself, whereas C++ is more focused on compile-time capabilities with some dynamic capabil...

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

   www.studytonight.com › difference-between

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   Objective C is a multi-paradigm programming language and a superset of C, while C is a structured programming language. Both languages are general-purpose programming languages, although each is primarily utilized for a specific category of applications. Objective C is mainly used for IOS and Mac application development, whereas C is often used ...

7. 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/

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   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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   What is Objective C used for?

   • Let’s get started. What is Objective C? Objective-C is a general-purpose, object-oriented programming language that was developed in the early 1980s by Brad Cox and Tom Love. Mainly, it is used for software development on Apple’s macOS, iOS (mobile), watchOS, and TVOS platforms.

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

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

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   Should I learn Objective C or C?

   • You will also find it easier to learn other day modern programming languages if you know C already. If you want to learn more about C, take this in depth C programming course. One major advantage that C has over Objective C is that it is lighter and programs take up a smaller execution and memory footprint.

   C Vs. Objective C : Which Should You Choose? - Udemy Blog

   blog.udemy.com/c-vs-objective-c/

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8. blog.udemy.com › c-vs-objective-cC Vs. Objective C : Which Should You Choose? - Udemy Blog

   blog.udemy.com › c-vs-objective-c

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   Objective C supports the concept of inheritance (though not multiple inheritance), polymorphism and data abstraction- something that C is lacking. Objective C lets you declare classes- blueprints for your objects, which makes it easier to write structured programs. Objective C is a “superset” of C. Everything you find in C, you find in ...