C language is a programming language closely related to human language.
In part ①
"If aaa is 6, input 3 to bbb"
In part ②
"For others (aaa is not 6), input 5 to ddd"
The instructions of the program are very close to English words.
Moreover, the C language grammar is basically the same even if the microcontroller type is different, so when writing a program for a different microcontroller, there is no need to learn a new programming language. (*)
For C language, ISO and ANSI jointly standardized the standard.
* Some microcontrollers are exceptions.
ISO：International Organization for Standardization
ANSI：American National Standards Institute