"Dark Horse Programmer" recognizes OC's first program (OBJECTIVE-C)

Features of OC

● On the basis of the C language, a minimal object-oriented syntax is added.

fully compatible with C language

You can mix C code, even C + + code, in OC code

applications that can use OC to develop Mac OS x platform and iOS platform

object-oriented versus process-oriented differences:

①oc is Object-oriented

②C is process-oriented

③ object-oriented and facing over-becoming is just two different ways to solve the problem

④-oriented process is only a matter of solving the problem, object-oriented is only to consider the object to solve the problem.

Key Words:

Example: @interface, @implementation, @end

Note: Basically all the keywords start with @

code Exercise (First OC program):

#import <foundation/foundation.h>int Main () {    ///NSLOG output is automatically wrapped    NSLog (@ "First OC program");        return 0;}

1. #import

①, like include, is used to copy the contents of a file

② can automatically prevent file contents from being copied multiple times

the role of the 2.Foundation framework

① the necessary framework for developing OC,IOS,MAC programs

② This framework contains a number of commonly used API (application programming interfaces)

③ Framework contains a lot of header files, if you want to use the entire framework of content, including its header file can--#import <Foundation/Foundation.h>

use of bool:

The nature of the bool type

Tupdef signed Char BOOL;

There are two values for variables of type bool: YES NO

#define YES (BOOL) 1

#define NO (BOOL) 0

Output of bool (As Integer)

NSLog (@ "%d%d", yes,no);

nslog differs from printf:

1.nslog receives the OC string as a parameter. printf receives the C language as a parameter in the string

2.nslog output is wrapped and will not wrap automatically after printf output

3. NSLog #import required to use <foundation/foundation.h>

4. Using printf requires #include<stdio.h>

"Dark Horse Programmer" recognizes OC's first program (OBJECTIVE-C)