What does def mean and what does de stand for?

As follows:

#ifdef：

If there is a definition, the general form of ifdef is: ifdef macro replaces the name of the segment endif

What it means: If the macro substitution name has been defined, the "segment" is compiled; If the macro substitution name following the ifdef is not defined, the segment is not compiled.

#ifndef：

If there is no definition of the general form of ifndef, it would be: ifndef macro substitution name Segment endif

What it means: if the macro substitution name after ifndef is not defined, then "segment 1" is compiled; If you define a macro substitution name after ifndef, the statement segment is not executed.

#undef：

The undef command can be used to delete a predefined macro definition.

The general form of the undef command is as follows: undef macro substitution.

c languageMeaning of define as an English word:

define is an English word, verb, noun, which, when used as a verb, means " define; Make it clear; stipulate", which when used as a noun means "(define) the name of a person; De Faun; (Portuguese) Define".

Phrase collocation: flow define the process definition.

define mask ; The world says the hood.

define byte ; Defining Byte Directives ; Pseudo-directives ; Byte definition.

The above content refers to Encyclopedia-define

Encyclopedia - define

English means awesome etc. You can look it up yourself.

On the computer, it's the module definition file. def file extension.

In the game, it's "defence.""Abbreviation of defense.

At the same time, it is also the name of the one-day Korean ** group "def tech".

DEF is also short for Game Dungeon.

The preposition de stands for subjectivity, which is equivalent to the second case in German and Russian.

The word order in French is different from the word order in Chinese, but it is the same as the word order in Russian, German, and Arabic. The second case or genitive case of Russian, German, and Arabic nouns is generally placed after the noun as a definite sentence to explain the relationship between the nouns, and of course, the second case of Russian and German nouns can also be placed after the verb or preposition as an object.

I hope I can help you with your doubts.

Return valve DE50 Balance valve DE25 Globe valve DE75, I want to know what DE stands for Diameter DE The diameter of the general plastic pipe is represented by DE in engineering The nominal diameter is the size of all pipeline accessories in the pipeline system expressed by numbers, and the nominal diameter is a convenient round integer for reference, and the processing size is only not strictly related. Nominal paths are marked with the letters "DN" followed by a number. Nominal diameter, also known as mean outside diameter.

This is due to the fact that the pipe is very thin from the metal pipe, and the outer diameter of the pipe is almost the same as the inner diameter of the pipe, so the average value of the outer diameter of the pipe and the inner diameter of the pipe is taken as the pipe diameter. DE is the nominal outer diameter, which refers to the outer diameter, generally speaking, from small to large, the specifications are roughly as follows: DE(mm): DE20, DE25, DE32, DE40, DE50, DE63, DE75, DE90, DE110, DE125, DE160, DE200, DE250, DE315......All the way up to DE800

de refers to pinyin, of, de, de......Generally refers to, conjunctions.

de is an English prefix, and the prefix de- comes from Latin and means"away from", so one of the meanings of this prefix is:"Leave"、"out"。

The words it forms have a certain regularity and are often expressed"Leave"This is a deep concept, and is often paired with prepositions such as from, e.g., dethrone, deport, deduce, derail, delete his name from the list of members. The train will depart from platform 2.

The prefix de- also denotes"Remove"、"Cancellation"and"Negative"、"None"、"On the contrary"meaning. For example: decamp, decode, deforest, decolonize, devaluation.

In addition, the prefix de- also indicates strengthening, for example, in the word devoid, de- strengthens "void" (empty), emphasizing "nothing, nothing".

def is one of the key words of the python language, which is used to define functions, and functions are one of the most important concepts in python programming, which can be understood as a complete and reusable piece of **.

A function, or subroutine, is a piece of block that can be called anywhere in the program, and you can pass arguments to it when the function is called, and the function can return a value or not return a value. Using functions can help developers better organize their programs and make them easier to reuse and maintain, while also avoiding duplication of writing.

In the Python language, you need to use the def keyword to define a function, which is followed by the function name, and the parameters of the function are placed in parentheses, and if there are no parameters, they are directly followed by an empty parentheses. The ** block in the process needs to be indented, which is also a unique syntax rule of the Python language, and the indented ** block is the corresponding executor of the function.

ifdef if there is a defined general form of ifdef:

If the macro substitution name has already been defined, the segment is compiled; If the macro substitution name following the ifdef is not defined, the segment is not compiled.

ifndef: If there is no definition, the general form of ifndef macro substitution statement endif means:

If the first friend does not define the macro substitution name after ifndef, the statement segment 1 is compiled. If you define a macro substitution name after ifndef, the statement segment is not executed. undef: The undef command can delete a predefined macro definition.

The general form of the undef command is as follows: undef macro substitution.

define is an English word, verb, noun, which, when used as a verb, means " define; Make it clear; stipulate", which when used as a noun means "(define) the name of a person; De Faun; (Portuguese) Define". Phrase collocation: flowdefine process definition, definemask definition frame; The boundary says that the hood frame definebyte gauges the definition byte; Defining Byte Directives ; Pseudo-instruction byte definition.

In Python, def means declarative function.

Python starts with a def function definition, followed by the function name, the parentheses inside the parameters of the function, the specific functional implementation of the function inside, and if you want the function to have a return value, use return in the logic in expressions.

expressions

instance def function():

print('this is a function')a = 1+2

print(a)

function, the function does not accept arguments, so the parentheses are empty inside, followed by the function of the function. If you run the script, you find that there is no output because we only define the number of spine functions, not the function. In this case, we enter the function in the python command prompt to call function(), note that the parentheses of the call function cannot be omitted.

The function inside the function will be executed, and the output will be: this is a function.