Language Translators
Translation and execution of programs
Instructions in a program can only be executed when written in machine code and loaded into the main memory of a computer.
Assembler
Compiler
Interpreter
Programming instructions written in any programming language other than machine code must be translated before they can be used.
The systems software used to translate a source program written in any language other than machine code are translators.
There are three types of translator available, each translator performs a different role.
Assemblers
Programs written in assembly language are translated into machine code by an assembler program.
Compilers and interpreters
Programs written in a high-level language can be either translated into machine code by a compiler program, or directly executed line-by-line using an interpreter program.
Assembler | Compiler | Interpreter | |
|---|---|---|---|
Source program written in | assembly language | high-level language | high-level language |
Machine dependent | yes | no | no |
Object program generated | yes, stored on disk or in main memory | yes, stored on disk or in main memory | no, instructions are executed under the control of the interpreter |
Each line of the source program generates | one machine code instruction, one to one translation | many machine code instructions, instruction explosion | many machine code instructions, instruction explosion |
Partial compiling and interpreting
In order to achieve shorter execution times, many high-level languages programs use a system that is partially compilation and partially interpretation.
The source code is checked and translated by a compiler into object code.
The compiled object code is a low-level machine independent code, called intermediate code, p-code or bytecode.
Source code:
print("Hello World")Bytecode:
1 0 LOAD NAME
2 LOAD CONST
(print)
0 (Hello World')
4 CALL FUNCTION1 (1 positional, keyword pair)
6 RETURNVALUEThe translator that can translate language as machine dependent:
The translator that generate object program(executable file):
The translator that translate language with one line to many lines machine code:
The translator that finds all errors in a program
The translator that is easier to develop and debug a program
An (IDE) is used by programmers to aid the writing and development of programs.
Integrated development environment (IDE)
An integrated development environment (IDE) is used by programmers to aid the writing and development of programs.
IDEs usually have
a source code editor
a compiler, an interpreter, or both
a run-time environment with a debugger
an auto-documenter
Features
coding
context-sensitive prompts
initial error detection
dynamic syntax checks
presentation
prettyprint
expandand collapse code blocks
debugging
single stepping
breakpoints
report window
Source code editor
A source code editor allows a program to be written and edited without the need to use a separate text editor.
Most source code editors colour code the words in the program and layout the program in a meaningful way (prettyprinting).
Compiler, an interpreter, or both
Most IDEs usually provide a compiler and/or an interpreter to run the program. The interpreter is often used for developing the program and the compiler to produce the final version of the object code.
Run-time environment with a debugger
A debugger is a program that runs the program under development and aids the process of debugging.
It allows the programmer to single step through the program a line at a time (single stepping) or to set a breakpoint to stop the execution of the program at a certain point in the source code.
A report window then shows the contents of the variables and expressions evaluated at that point in the program.
This allows the programmer to see if there are any logic errors in the program and check that the program works as intended.
Auto-documenter
Most IDEs usually provide an auto-documenter to explain the function and purpose of programming code.
An IDE usually have: