What are high- level languages?

Answer 1

High-level languages are languages that have little or no dependency upon the machine architecture. Code is written with a high-level of abstraction (hence they are classed high-level) which makes it much easier to port the same source code to any machine that has a compatible compiler or interpreter to produce the low-level machine code. Low-level code is non-portable code.

Some languages, including C and C++, are both low-level and high-level, often classed as mid-level languages. These languages allow programmers to write both portable and non-portable code within the same program. However, the non-portable code can be rendered portable by crafting alternative versions of the non-portable code for each supported platform, filtering them through the use of precompiler directives. In this way, the compiler only sees the code that is specific to the platform and will compile accordingly.

Java is an extremely high-level language that is both compiled and interpreted. Unlike normal compiled languages which compile to machine-dependent code and therefore need to be recompiled separately for each supported platform, Java compiles to byte code which can then be executed upon any machine without recompiling. To achieve this, the target machine must be running an interpreter program known as the Java virtual machine (or JVM) where each physical machine has its own implementation of the JVM. In other words, source code is targeted towards the same, non-physical machine. The upside is that compilations are highly portable. The downside is that Java programs do not perform well compared to their compiled language equivalents and are only suitable for high-level applications software (you cannot write low-level software such as operating system kernels and drivers).