Modern IT world has created hundreds of programming languages. Each of them has its own pros and cons. If you have a job to do – what language should you choose?
The short answer to this question is: it depends, because depending on the kind of functionality that you need, a different language may be optimal. In this article I’ll try to describe the most popular kinds of languages, their advantages and disadvantages as well as the kinds of applications that you should use them for.
High or low level?
A useful distinction for us will be whether the language is high-level or low-level. Low level languages describe directly operations that need to be performed by the underlying hardware. The higher level the language is, the more abstract it gets (for example it can be run on a variety of processors) and the more functionality is automated (for example memory management). Unfortunately high abstraction and automation come with a price. The biggest problem is overhead of the layer that translates high-level commands into hardware operations. In case of scripting languages the overhead makes the application run around 100 times slower than a similar application written in a low level language. Somebody could now think, that the high level languages do not make sense if they slow down your system to this level. But it’s a mistake. In the modern world the cost of a processor is relatively low compared to the cost of writing software. High level languages can highly decrease time needed to finish all your projects and limit potential problems with it. This is why the modern world generally tends to move in the direction of high level languages.
If you want to write an application, you can usually choose to either use low level language and slowly build a fast-running software, or use a high level language and quickly build a slow-running solution.
Different tasks may require different choices. For example, websites are usually built using high level scripting languages. But embedded devices (that are mass-produced in as many as millions of pieces) are commonly built using low level C language and this makes it is possible to use cheaper processors and lower the unit cost.
Assembler is a class of languages that represent the lowest possible level. A characteristic feature of those languages is that each existing processor has its own assembler language and an application written for one processor cannot be run on other processor.
Currently assembler is relatively rarely used. It is sometimes a language of choice for programming microcontrollers and – of course – compilators. Its organization makes it impossible to write any big software because the code gets quickly difficult to maintain.
C is currently the most popular procedural language. This means, that its syntax is based on procedures and structures of data. A disadvantage of C is not full portability between platforms. Although code written for one processor can be compiled for another one, in practice there are differences in details between microprocessors and C does not always hide the complexity. For example, an integer variable (int) has different sizes depending on the microprocessor used. A similar problem is causes by the so called endianness – the order of bytes in bigger structures. Different processors organize their memory in different ways and it sometimes causes problems when code gets migrated from one platform to another. To write a multiplatform application in C, you need to hire really good programmers who are conscious of the challenges of running C code on multiple processors and know how to handle them.
Currently C language is mostly used to write embedded software and operating systems.
C++ language is a younger cousin of C. Actually it an object oriented extension to C. C++ is replacing C because of its ability to create object oriented design that makes building complex application much easier. At the same time object oriented design does not introduce important overhead. If your platform supports C++ compiler, you probably should use it instead of C language.
C and C++ (and a recent, not yet fully developed, Rust language) are the only languages that can be used to build real time solutions, for example audio streaming in Skype. For a long time C++ was also used in desktop applications and although it gets superseded by C# and Java, it is still quite popular because of market inertia. Another area of popularity is game development, where C++ has been definitely the most popular choice for many years.
Java and C# belong to the first generation of languages that are 100% independent on the processors they are running on. Thanks to it each application written in Java should (at leas in theory) work on each operating system and on each microprocessor. Practice sometimes shows that there are often small differences between platforms that do cause some problems, but contrary to C and C++ those problem are rather uncommon.
Java and C# introduced one more very important mechanism that solved ages-old programming problem – memory leaks. C or C++ programmer needs to remember to free previously allocated memory when it is no longer needed. C# and Java discover that the given object is no longer referenced and free it for you. They eliminate hundreds of difficult problems and reduce programmers’ work. A disadvantage of garbage collection is its unpredictability that makes Java and C# unsuitable for writing real time solutions.
Java and C# are frequently used to create office software (for example Word) and business web services. There was research made on productivity in C++ and Java language and according to it you need only half as much time to write the same application in Java compared to C++. Unfortunately, then it runs between 1.4 and 5 times slower.
The last kind of programming languages are scripting languages. Frequently they are also called dynamically typed (formally this is not the same but most often scripting languages are also dynamically typed). What is characteristic in those languages is that objects do not have predefined types an only when you perform a given operation on them it is checked if this operation is possible. To state this in a more metaphorical way, scripting languages allow you to add five carrots to a car and during this operation raise an exception. Statically typed languages such as C++ or Java do not let you add incompatible types at all and they report an error during compilation.
Scripting languages are commonly used in web context for generating and maintaining websites, applications running in clouds and for automation and writing short programs on desktop computers. Scripting languages are also frequently used to perform integration tests of applications written in other languages.