Software Development Overview

(i) Software development Overview

1.1 software, programs and computer languages

Software is a collection of one or more program files that are written to accomplish some specific function

A computer is made up of electronic components .

1.2 Development of the programming language

1.2.1 Machine language

The characteristics of electronic components are that they have two very stable states: conductive or non-conductive. The early computer programmer used 0 to indicate the state of the computer's non-power, using 1 to indicate the state of the computer's power, and then implement the rounding mechanism through the integrated circuit.

Computers can only recognize 0 or 1

* Decimal number: The lowest bit is called bit, the high one is called 10 bit, in the high one bit hundred.

* Binary number: The lowest bit is recognized as the bit digit, but here the bit is called 1 bits.

* 00: It's all 0, so it's 0.

The *01:2 bit is 0, 1 bits is 1, 0 2 and one 1, so it is 1.

The *10:2 bit is 1, 1 bits is 0, it represents a 2 and 0 1, so it is 2.

1.2.2 Assembly language

The language of the symbolic representation of a fixed binary instruction is assembly

1.2.3 High-level language

1.3 Basic methods and steps of software development

program = data structure + algorithm

1. Analyze the problem and set up the data model

2. Real data structure and algorithm

3. Writing procedures

4. Debug program

1.3.1 Algorithm

* Poor: An algorithm must be terminated after performing a limited number of operation steps.

* Certainty: The meaning of each step in the algorithm must be deterministic.

* Validity: Each step in the algorithm should be executed effectively, and an unenforceable operation is not valid.

* There are 0 or more inputs: the input here refers to the initial data needed before the algorithm starts.

* There is one or more outputs: the so-called output refers to a variable that has a certain relationship with the input, and at least one output in a complete algorithm.

1.3.2 Encoding Implementation

1. Write source code

2. Compile the source code into the target code

3, the connection target code becomes the execution program

1) Source Code

Binary files consist of binary numbers, all binary numbers are composed of 0 and 1, each 0 or 1 is called a bits or a bit, in the computer, we make 8 bits of a byte, 1024 bytes into a kilobyte, 1024 is a megabyte.

2) compiling the source code

There is a clear difference between the compiler and the translator, where the compiler translates the entire program into binary code at a time, and the translator converts a line of code into a set of binary instructions and executes the instructions.

3) Connection

4) Debug Program

                                         

Software Development Overview