What is high level languages in computer?

Answer 1

The way a computer works is by special switches opening and closing each other in special ways, much in the way that the wheels in gears control each other's turning. This doesn't sound like much, but it is enough for the computer to get data, calculate answers to problems, and output the answers when and wherever they are needed.

However, you cannot get such answers just by throwing a heap of switches together; you must have JUST the right switches doing JUST the right things at JUST the right time, or nothing useful will happen.

To do this one needs to be able to set the right switches at the start of the problem, and just as it is no good asking your calculator for the answer to a sum if you key in the wrong numbers, just so it is necessary to get just the right starting steps and all the right running steps in the right place and time. So for example, we might give the following three instructions written in hexadecimal for a certain kind of computer:

5810A324 5C10A328 5010A32C.

It means something like "take the number in this place, multiply it by the number in that place, and store the answer in that other place. This is already written in a very much simpler way than showing the actions of the switches, but it is not easy to read. We call this a very low-level language, "machine language".

It is a difficult and expensive business to write programs in machine language, especially long programs with thousands or even millions of instructions, and so people wrote other programs that could take what we call mnemonic instructions, easier for humans to read, and change them into machine language to give to the computer. Then we could write our three instructions in mnemonics that might read:

L 1, PRICE (Load PRICE for working on)

M 1,QUANTITY (Multiply the PRICE by the QUANTITY)

ST 1,COST (Store the answer in the place for the total COST)

This is a little better and easier to work with, but it is still just one machine instruction for each program instruction, so it is still what we call a low-level language. We call such a language Assembly language.

But if we make a language that looks more like our own human language, and write a program that can translate a single human instruction into many machine instructions, letting the computer do the hard, confusing bits, then we might write something like:

MULTIPLY PRICE BY QUANTITY GIVING COST.

This is a lot better, giving us three machine instructions for a single human language instruction. Some other instructions could give us hundreds of machine instructions for a single human instruction. When we have that, then are dealing with a high level language. It automatically gives us many machine instructions for a single human instruction.

Nowadays we more often deal with languages that give us very large numbers of machine language instructions that don't at all look like the human instructions, for instance, REPORT SALARY DEPOSITS IN EMPLOYEE SEQUENCE. Such an accountancy program is a far higher level language than one that talks about multiplication and so on. In such very high level languages we need not even understand how the the computer does it, or whether it needs to multiply things at all.