C Language Section II overview

1. Pre-school Reminders
2. In fact, iOS development is the development of Iphone\ipad software, and to develop a software, first of all to learn the programming language
3. iOS development needs to learn the main programming languages are: C language, C + +, objective-c, where C + +, Objective-c are based on the C language, derived from the C language. Therefore, the C language is the basis for developing iOS software.
4. From now on, sink your mind to learn the legendary C language and learn its grammar.
5. Formal study before, first remind a sentence: Learning a language grammar is more boring things, very much like in the study of a few, it is impossible to learn C grammar process can immediately make some good-looking iphone software interface effect
6. We should sink to live gas, so-called Kujinganlai, no grammar accumulation, how to write a good-looking interface?

1. Computer and software knowledge

1. Principles of computer operation
   1. Basic hardware: Hard disk, memory, CPU
   2. Coordination of operations between individual components (right)

1. Computers can only recognize 0 and 1
   1. Directives consisting of 0 and 1
   2. Data consisting of 0 and 1

1. Computer and Software connections
   1. Basic concepts of software: a collection of instructions
   2. Software Installation and Operation process

• Installed on the hard disk
• Running in memory

1. Why develop software: Write instructions that can control your computer

1. Computer language
   1. A language for dealing with computers
   2. Easy to write a series of instructions

1. History of computer language

1. Machine language
   1. Summary: All code is only 0 and 1, each instruction is called "Machine instruction"
   2. Advantages

• Code can be directly recognized by the computer, directly to the hardware, program execution efficiency is very high
• can directly hardware devices, such as disk et

1. Disadvantages

• The program is all 0 and 1 of the instruction code, poor readability, but also error-prone

• The dependence on hardware is strong, so the machine language of different models of computers is not the same. That is to say, if 2 different models of machines want to achieve the same function, you need to write 2 sets of completely different code
• To memorize the meaning of all the instructions and instructions of the computer used, the instructions are many and difficult to remember.

1. Use occasions

In summary, machine language is difficult to master and promote , now in addition to computer manufacturers of professionals, the vast majority of programmers have no longer to learn machine language

1. Assembly
   1. Introduction: Replace machine instructions with English words and other symbols
   2. Advantages

• like machine language, direct access to , Control the various computer Hardware Equipment
• Low memory footprint and fast execution speed

1. Disadvantages

• Different machines have different assembly language syntax and compilers, the code lacks portability, that is, a program can only be run on one machine, and can not be run on another machine
• Symbols are very many, difficult to remember, even the completion of simple functions also require a lot of assembly language code, it is easy to produce bugs, difficult to debug
• The hardware must be well understood, the development efficiency is low, the cycle is long and monotonous

1. Use occasions

• Operating system kernel, drivers, microcontroller programs
• Encryption, decryption and decoding of software
• Manufacture and prevention of virus
• Debugging and analysis of the program

1. Advanced language
   1. Introduction: Close to natural language
   2. Advantages

• Simple, easy to use, easy to understand, syntax and structure similar to general English
• Away from the direct operation of the hardware, so that the average person after learning can be programmed, without being too familiar with the hardware knowledge
• A program can also be run on different machines, with portability

1. Disadvantages

• The program cannot be directly recognized by the computer and needs to be translated into binary instructions by the compiler before it can be run to the computer

1. Category: C language, C + +, C #, Java, objective-c, etc.

1. Comparison of three different languages

To write a program that calculates the last one, using machine language, assembly language, C language (high-level language), respectively

1. Machine language: It's a heavenly book!!!

10111000 00000001

00000000 00000101

00000001 00000000

1. Assembly language: Readability a little better, but trouble

MOV ax,1

ADD ax,1

1. C Language: Streamlined, easy to understand

Up

1. Introduction to C language

1. The reason for learning C language first
   1. OC based on C
   2. OC and C's thought and grammar are different in many places, and OC can be mixed with C
   3. C is the classic of all programming languages, many high-level languages are derived from C language, such as C + +, C #, OBJECTIVE-C, etc.

1. History
   1. The C language was invented in 1972 and was first used to rewrite the Uinx operating system (Unix was written primarily in assembly language, which laid the foundation of the operating system)
   2. With the success of Unix operating system, C language has been greatly promoted, has been used in large, medium and small, micro-host, is still the world's most popular, the most widely used high-level programming language One
   3. C language is a process-oriented language, non-object-oriented language

1. Characteristics
   1. Rich operator
   2. Rich data types
   3. Can operate the hardware directly
   4. Efficient target Code
   5. Portability is good

1. Main purpose
   1. Write system software, graphics processing, SCM program, Embedded system development
   2. Write a game plug-in
   3. Writing Android Programs
   4. Writing iOS programs

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1. Version issue
   1. 1983 National Bureau of Standards (American Nation Standards Institute, ANSI) set up a committee to begin work on the C language standard
   2. 1989 C language Standard is approved, this version of the C language standard is commonly referred to as ANSI C
   3. In 1999, ISO also revised the C language standard, on the basis of the basic retention of the original C language features, in response to the needs of the need to add some features, named C99
   4. December 8, 2011, ISO formally publishes the new International standard of C language draft: C11

C Language Section II overview