Programmers have a variety of tools available to enhance the software development process. Some
common tools include:
• Editors:
An editor allows the programmer to enter the program source code and save it to files.
Most programming editors increase programmer productivity by using colors to highlight language
features. The syntax of a language refers to the way pieces of the language are arranged to make
well-formed sentences. To illustrate, the sentence
The tall boy runs quickly to the door.
uses proper English syntax. By comparison, the sentence
Boy the tall runs door to quickly the.
is not correct syntactically. It uses the same words as the original sentence, but their arrangement
does not follow the rules of English.
Similarly, programming languages have strict syntax rules that programmers must follow to create
well-formed programs. Only well-formed programs are acceptable for translation into executable
machine code. Some syntax-aware editors can use colors or other special annotations to alert programmers of syntax errors during the editing process.
• Compilers. A compiler translates the source code to target code. The target code may be the machine
language for a particular platform or embedded device. The target code could be another source
language; for example, the earliest C++ compiler translated C++ into C, another higher-level language.
The resulting C code was then processed by a C compiler to produce an executable program. (C++)compilers today translate C++ directly into machine language.) Compilers translate the contents of a
source file and produce a file containing all the target code. Popular compiled languages include C,
C++, Java, C#.========================================================================
• Interpreters:
An interpreter is like a compiler, in that it translates higher-level source code into target code (usually machine language). It works differently, however. While a compiler produces an executable program that may run many times with no additional translation needed, an interpreter translates source code statements into machine language each time a user runs the program. A compiled program does not need to be recompiled to run, but an interpreted program must be reinterpreted each time it executes. For this reason interpreted languages are often refered to as scripting languages. The interpreter in essence reads the script, where the script is the source code of the program. In general, compiled programs execute more quickly than interpreted programs because the translation activity occurs only once. Interpreted programs, on the other hand, can run as is on any platform with an appropriate interpreter; they do not need to be recompiled to run on a different platform. Python, for example, is used mainly as an interpreted language, but compilers for it are available. Interpreted languages are better suited for dynamic, explorative development which many people feel is ideal for beginning programmers. Popular scripting languages include Python, Ruby, Perl, and, for web browsers, Javascript.
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• Debuggers:
A debugger allows a programmer to more easily trace a program’s execution in order to locate and correct errors in the program’s implementation. With a debugger, a developer can simultaneously run a program and see which line in the source code is responsible for the program’s current actions. The programmer can watch the values of variables and other program elements to see if their values change as expected. Debuggers are valuable for locating errors (also called bugs) and repairing programs that contain errors. (See Section 3.6 for more information about programming errors.)
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• Profilers:
A profiler collects statistics about a program’s execution allowing developers to tune appropriate parts of the program to improve its overall performance. A profiler indicates how many times a portion of a program is executed during a particular run, and how long that portion takes to execute. Developers also can use profilers for testing purposes to ensure all the code in a program is actually being used somewhere during testing. This is known as coverage. It is common for software to fail after its release because users exercise some part of the program that was not executed anytime during testing. The main purpose of profiling is to find the parts of a program that can be improved to make the program run faster.
Many developers use integrated development environments (IDEs). An IDE includes editors, debuggers, and other programming aids in one comprehensive program. Python IDEs include Wingware, Enthought, and IDLE. Despite the wide variety of tools (and tool vendors’ claims), the programming process for all but trivial programs is not automatic. Good tools are valuable and certainly increase the productivity of developers, but they cannot write software. There are no substitutes for sound logical thinking, creativity, common sense, and, of course, programming experience
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