C language learned by suffering

C language learned by suffering

In the previous section, you simply said, make the program work.
This section will discuss that in more detail.

To begin with, the program you just described is nothing more than an ordinary string of characters.
You've probably heard that computers run on binary numbers.
Why would a computer running on binary numbers recognize and work with strings?

Essentially, for a computer, the only instructions it can understand are those written in binary numbers.
The instruction ・・・・, written in binary, is what is called machine language (machine language ).


This is just a bunch of bullshit 0s and 1s, but it is the image.
Any computer, ancient or modern, can only recognize this form of instruction.

Computers can only understand machine language (machine language).
In fact, such programs were used in the early days of computers.
A vast number of zeros and ones were entered by flipping a toggle-type switch.

However, any amount of this is going to be daunting.
So, the first thought was to shrink the digits of the numbers.


This is the so-called hexadecimal representation.
Four binary digits can be represented by a single hexadecimal digit, which is shorter.
Then, an assembler was also conceived that symbolized each of these numbers.


Although this symbolization has made programming much more efficient, the
They are still symbols that are difficult for ordinary people to understand and handle.
The world's first programming language, FORTRAN, changed this dramatically.


At this point, it is quite close to English text and formulas, and even ordinary people can understand it if they study it.
The C language is also one of these high-level languages, languages that are close to human language.

High-level languages are human-inspired languages and therefore cannot be understood by computers.
In order for a computer to understand this, translation is necessary.
It is basically the same as translating English into Japanese.

This task, of course, can be done manually by humans.
That is not much different from programming in machine language after all.
Therefore, software exists to perform the translation.

There are two main translation methods. In the case of the C language, the method that translates everything at once is used.




The software that compiles and translates this translation is called a compiler.
We have already explained how to obtain and use a compiler, and this software is necessary for this purpose.


The compiler actually works in a three-step mechanism.

First, the string is adjusted by software called a preprocessor.
Whitespace and line breaks are combined and symbols are replaced to make the program easier to analyze.
The #define pseudo instruction and other instructions described below are also processed here.

Next, the compiler compiles the file, and optimization is performed at this time.
The same C program can run at different speeds depending on how it is translated.
The compiler translates the data to be faster.


Finally, the translated machine language programs are combined by software called a linker.
Combining with a linker is called linking.
Linking turns machine language data into an executable file.


*Pre-processing, compilation, and linking are sometimes collectively referred to as compilation.
Also, even the creation of an executable file is sometimes collectively referred to as build.

The file that becomes an executable (in essence, an EXE file) is
It can be run as an application.

These series of tasks are now fully automated, so that
We are usually not particularly aware of this, but software is created that can operate at the push of a button.