It's not a document or a tutorial. It's just supervising myself to learn C language by clocking in and recording only some small notes. If there is any mistake, thank you very much for pointing it out! ! !

One, clion shortcut keys

Formatting symbols:

d is an integer
u unsigned integer
ll long integer
hd means short integer
s is a string
x is hexadecimal
oct is octal
Using the limits.h file, you can print out the maximum range and minimum range of a certain type such as INT_MAX, INT_MIN, etc.
The number of bytes occupied by the data type is different on different systems

Char is actually a number internally, mapped from the ASCII table
When assigning a character variable to a character, you can assign the character directly, or / followed by an octal or hexadecimal number, and the corresponding value is converted to the corresponding decimal, and then compared to the ASCII table. For example,'\61' and'\x31' both represent 49, and 49 in the ASCII table is "1", so'\61' is '1'.
\n:newline
\b:backspace
\r:return
\t:table
':' character literal
":" string literal
The ASCII character set is American and is suitable for English. Char is a byte, while Chinese corresponds to Unicode. Instead of using char, use wchar_t (wide character) added after c95. In smvc, it is actually one Unsigned short integer, occupying 2 bytes. (Add an L before the literal amount)
But when using utf-8 encoding, it is not a character, but a byte.
Use %d to print out the number of'中', which is the code point (Code Point) corresponding to Unicode
When wide character escapes hexadecimal not the beginning of'\x', but the code point of'\u' plus unicode.

Float is single-precision. The c standard does not specify how many bytes it occupies (4 bytes in my MSVC environment). Instead, it specifies that it can represent at least 6 significant digits, ranging from -10 ^{-37 to 10} 37.
double is double precision (8 bytes in MSVC)
Floating-point data argument without f defaults to double precision
Floating point data is expressed as 1.2345*e^4 using scientific notation 12345
Float is 4 bytes, then it is 32 bits, take out 8 bits to represent the exponent (exponent of science and technology method e), 23 bits to represent the number of digits (the number after the decimal point), and the number before the decimal point is called the hidden place.

The const definition is called a read-only variable. After a pointer points to it, you can still modify it! ! !
Macros defined by #define will be preprocessed during compilation.
Corresponding to undef, cancel macro
True constants are independent variables!

MSVC does not support standards after C90
Windows often uses JBK encoding. In today's study, I clearly typed the; symbol in English, but an error was reported that it could not be found. The reason is that our file uses UTF-8 encoding, and MSVC is JBK, so we need to transfer the file Encoding method.