Pre-preparation for OC language

Pre-preparation for OC language

I. INTRODUCTION of OC

OC language on the basis of the C language, the addition of a layer of the smallest object-oriented syntax, fully compatible with the C language, in the OC code, can be mixed with C, or even C + + code.

You can use OC to develop applications for Mac OSX platforms and iOS platforms.

Extended Name: C language-.c OC language.-M compatible c++.-mm

Note: In fact, C language and OC or even any language is just for us to achieve some functions, to achieve some effect and the use of tools, aside from the grammatical differences, I think the most important thing is to solve the problem when the angle and method of thinking is different, but this also constitutes the importance of learning a language.

Second, Syntax preview

(i) Keywords

Basically all of the keywords are at the beginning of the (in order to distinguish with the C keyword), such as @interface @implementation @public, and so on, a small part does not start with @, such as id,_cmd, etc.

(b) The string begins with @

C-language string: "Hello"

OC language string: @ "Hello"

(iii) Other grammatical

Basic type: 5 types, added Boolean type

Nil equals null, which is 0.

Screen output: NSLog (@ "Hello");//Wrap Line

NSLog (@ "Age is%d", 2);

Third, OC program development process

#import预处理指令有两个作用: (1) As with # include, the Copy file contents (2) can automatically prevent the contents of the file from being copied repeatedly

The program compiles the connection process:

source file (. m)---(compile)----> destination file (. 0)-----(link)----> executable (. Out)

Foundation Framework. What should I do if I want to use all the header files in the frame? Contains the primary header file for the framework. The primary header file is the most important header file in a framework, with the main header filename and frame name consistent for each frame.

such as #import<foundation/foundation.h>

Run the following procedure:

(1) Write the OC source file. M. C

(2) Compiling files cc-c xx.m xxx.c

(3) Link cc xx.o xxx.o-framework Foundation

(4) run./a.out

Iv. Types of Supplements

Int Main ()

{

BOOL B=yes;

BOOL B1=no;

BOOL b2=1;//YES

BOOL b3=2;//NO

NSLog (@ "%i", b);

}

The bool type is consistent with other types of usage, and the nature of the bool type is char type, defined as follows:

Typedef signed Char BOOL

Macro definition:

#define YES (BOOL) 1

#define NO (BOOL) 0

The output of a Boolean type is generally used as an integer.

Pre-preparation for OC language