Programming Language. Machine Code. CS200: Computer Science I. Module 3 Programming Languages

Transcription

1 CS200: Computer Science I Module 3 Programming Languages Kevin Sahr, PhD Department of Computer Science Southern Oregon University 1 Programming Language a language for writing programs that tell the computer what you want it to do defined by specifying the syntax and semantics of the statements used to create programs 2 Syntax & Semantics syntax: rules that specify what makes a valid statement in the language like the rules of grammar for the english language semantics: the interpretation of language statements like determining the meaning of an english sentence what does it tell the computer to do? 3 Machine Code Every CPU understands a set of simple instructions represented by binary numbers called the machine code of the CPU unique to that CPU on early computers, programs were written in machine code PROBLEM: very hard for humans to understand! 4

2 High Level Programming Languages instructions are english-like one high level instruction can map to multiple machine code instructions 5 Source Code High level programs are written in text files called source code files The high level instructions must be translated into machine code instructions before the CPU can execute them 6 Compilation Compilation is the process of translating source code files into machine code files The result is usually called a binary or executable file A compiler is a program that performs compilation 7 The Programming Process Writing programs in a compiled high level language is a 3-step process: 1. Create the source code file 2. Compile the source code file 3. Execute the executable 8

3 Programming Tools The programming process requires 3 tools: 1. A text editor to create/edit the source code file 2. A compiler to compile the source code file 3. A way of executing/testing the binary file 9 Programming Tools These tools can be separate applications, OR They can be bundled together into a single application called an Integrated Development Environment (IDE) We will use an IDE called JGrasp reasonably powerful relatively simple interface free 10 Java is a compiled high level 11 FYI/Non-testable This is a simplification. The situation in Java is actually a little more complex... 12

4 Java is a compiled high level 13 Java Source Code Source code files in Java have the file suffix.java EX: a program called MyProgram would be written in a source code file called MyProgram.java NOTE: Java is case sensitive! to Java, MyProgram.java and myprogram.java are two different files 14 Java Class Files The Java compiler produces binary files with: the same file prefix as the source code file, and the file suffix.class EX: compiling MyProgram.java would create the binary file MyProgram.class compiled Java files are often referred to as class files 15 Our First Java Program In Lab 1 we will create, compile, and execute a simple Java program using the JGrasp IDE 16

5 Module 3 Vocabulary syntax semantics machine code high level programming language source code file compilation/compiler binary/executable file integrated development environment (IDE) JGrasp Java class file 17 Questions? Kevin at sahrk@sou.edu 18