01-c Language Overview

First, pre-school reminders

1. In fact, iOS development is the development of Iphone\ipad software, and to develop a software, first of all to learn the programming language

2. 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 C language. Therefore, the C language is the basis for developing iOS software.

3. From now on, sink your mind to learn the legendary C language and learn its grammar.

4. Before the formal study, the first reminder: 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

5. We should sink to live gas, so-called Kujinganlai, no grammar accumulation, how can you write a good-looking interface?

First, pre-school reminders

1. In fact, iOS development is the development of Iphone\ipad software, and to develop a software, first of all to learn the programming language

2. 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 C language. Therefore, the C language is the basis for developing iOS software.

3. From now on, sink your mind to learn the legendary C language and learn its grammar.

4. Before the formal study, the first reminder: 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

5. We should sink to live gas, so-called Kujinganlai, no grammar accumulation, how can you write a good-looking interface? Second, computer and software knowledge 1, the principle of computer operation

1) Hardware basic components: Hard disk, memory, CPU

2) coordination of operations between components (right) 2. Computers can only recognize 0 and 1

1) instructions consisting of 0 and 1

2) 0 and 1 are composed of data 3. Computer and Software connections

1) Basic concept of the software: a set of instructions

2) Software Installation and operation process

U mounted on hard drive

U Run in memory

3) Why Develop software: Write command 4 that can control your computer. Computer language

1) A language that deals with computers

2) Easy to write a series of instructions three, the history of computer language

1. Machine language

1) Introduction: All code inside only 0 and 1, each instruction is called "Machine instruction"

2) Advantages

U code can be directly recognized by the computer, directly to the hardware, program execution efficiency is very high

u can directly access and control the various hardware devices of the computer, such as disk, memory, CPU, I/O port, etc.

3) Disadvantages

The U program is full of 0 and 1 instruction codes with poor readability and error-prone

U is very dependent on hardware, so the machine language of different models of computer 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

You have to memorize all the instructions and instructions of the computer you are using, and the instructions are more difficult to remember.

4) Use the occasion

To sum up, 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 2. Assembly

1) Introduction: Replace machine instructions with English words and other symbols

2) Advantages

U like machine language, you can directly access, control the computer's various hardware devices

You use less memory and perform faster

3) Disadvantages

U different machines have different assembly language syntax and compilers, code lacks portability, that is, a program can only be run on one machine and not run on another machine

The U symbol is very many, difficult to remember, even if the completion of simple functions also require a lot of assembly language code, it is easy to produce bugs, difficult to debug

U must know the hardware very well, the development efficiency is very low, the cycle is long and monotonous

4) Use the occasion

U operating system kernel, driver, microcontroller program

Encryption, decryption and decoding of U software

Manufacture and prevention of U virus

U program debugging, Analysis 3. Advanced language

1) Introduction: Close to natural language

2) Advantages

U simple, easy to use, easy to understand, syntax and structure similar to general English

U 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

U a program can also be run on different machines, with portability

3) Disadvantages

U program can not be directly recognized by the computer, it needs to be translated into binary instructions by the compiler to run to the computer

4) Kinds: C language, C + +, C #, Java, OBJECTIVE-C, etc. 4. 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 is a heavenly book!!!

10111000 00000001

00000000 00000101

00000001 00000000

2) Assembly language: Readability a little better, but trouble

MOV ax,1

ADD ax,1

3) C language: Streamlined, easy to understand

Four, C language introduction 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. 2. 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

3. Features

1) Rich operator

2) Rich data types

3) can operate the hardware directly

4) Efficient target code

5) Portability Good 4. Main purpose

1) write system software, graphics processing, single-chip microcomputer program, embedded system development

2) write the game plug-in

3) Writing Android programs

4) Writing iOS programs

...... 5. Version issues

1) In 1983, the U.S. National Bureau of Standards (American Nation Standards Institute, abbreviated as 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 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

01-c Language Overview