Why do all the subscripts in computer languages start from 0?

Why do the subscripts in computer languages 0start from the beginning?

• With the popularization of the Internet, the phenomenon of pan-coding and agriculturalization of various types of work has become more and more obvious. For those who have not learned the basic theory of computers, there may always be a puzzle:
• Why do the subscripts of data containers in computer languages 0start from the beginning? Not from the 1beginning?

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To find the answer to this question, we can first describe how the computer stores and calls data at the bottom.

• Take pythonthe strdata format in as an example:
• In fact, there is no 字符串storage unit called " " in the chip . The memory is essentially a large chip, composed of countless storage units, arranged in sequence, and the computer numbers these boxes.

• These storage units are very small, we call them bytes ( byte), usually only 8 bits ( bit).
• How small is it? It can only represent a letter or number, and requires 2 storage units to represent a Chinese character.
• Therefore, if you store an article, many such storage units will be used.

After talking about the data format, let's analyze a concept-storage method.

• When we name a variable, the computer will tell the memory that a piece of data will be stored next and carry some basic information to the computer, and then the memory will wait for us to assign a value to this variable.
• What does the computer tell memory when naming variables? Take string as an example:

• The computer will first find a blank storage unit in the memory. Let us first assume that this is the 100th storage unit (referred to later No.100).
• When it No.100is determined that it is used to store sentencethis string, the computer will tell the memory that it sentenceis equal No.100to the first string of strings.

• Let's sentenceassign a value so that we can better explain it later:
• Because there No.100can only be one byte and only one letter can be stored, No.100only the letter " h" is actually stored in it ,
• The following ello word!characters of " " are stored in No.101~ No.111storage unit respectively.

After the above basic information is introduced, we can return to today's topic-the subscript issue.

• For memory, it sentenceis No.100synonymous, so when you want to call sentence, you are actually calling No.100the string from the beginning
• Here is a small explanation: In fact No.112, there will be a "terminator" in the position
• Therefore sentence, when the computer obtains it, it can be understood that the computer sends an instruction to the memory: " Fetch characters from No.100( sentence) and continue to the terminator".

• And when you use sentence[n]this format, the real instruction of the computer is to get the data on the " No.100( sentence) +  n" storage unit;

• For example, sentence[6]equivalent No.100+6, that is, No.106data on the storage unit, that is w.
• It sentence[0]is to fetch No.100+0the data.

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Of course, Python simplifies a lot from the syntax, let us save a lot of extra steps. But in essence, the representation logic of subscripts is based on this underlying logic. One pass Belden, I hope this post can help you to relieve the confusion about subscripts.

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