================ Chapter one =================
C The advantages of ： Design features , Efficiency , Portability , Powerful functionality and flexibility , For programmers
shortcoming ： Freedom of expression increases the risk of procedure , The price of freedom is always vigilance
use C The seven steps of ： Define program objectives , Design procedure , Write code , compile , Run the program , Testing and commissioning procedures , Maintenance and modification procedures , notes
C Programming mechanism of language ： The compiler converts the source code into a target executable file （ Is an incomplete program that contains machine code ）, The linker will precompile the library code , The standard startup code and object code of the system are combined together , Convert to executable , This file contains machine code that can be run .
C Language standards ：ANSI/ISO C standard → C90 standard → C99 standard
================ Chapter two =================
C Interpretation of procedures
#include <stdio.h>
This is a preprocessor instruction
stdio.h Represents the input and output header file standard input/output header
Another common pitfall of compilers is that the errors found are one line behind the real ones
Debugging code should be faithful to the actual code
================ Chapter three =================
C Data type graph of language
Integer type
include (unsigned)long long int ,(unsigned) long int, (unsigned) int,(unsigned)
short int,(unsigned) char
System processing int Type of data is the fastest , According to the size of the storage space, the processing speed of others slows down in turn
The content expressed in single quotation marks character , The content expressed in double quotation marks character string
In the same system ：long long int (8 byte ) > long int (4 byte ) > int (2 ~ 4 byte ) > short (2 byte ) >
char (1 byte )
It can be used LL,L,LU,LLU As a suffix to a number, it identifies different data types `
The overflow of integer data type is a problem worth studying , It includes the following aspects ：
1, Overflow of conversions between different data types
2, Overflow occurred in signed and unsigned data type conversion
Floating Point Types
float (4 byte , Significant number at least 6 position ) > double (8 byte , Significant number at least 10 position ) > long double ( at least 8 byte , Significant number at least 10 position )
The overflow and underflow of floating-point data type is worth studying , It includes the following aspects ：
1, Data overflow
2, Data underflow
Complex and imaginary types complex.h
_Complex _Imaginary
Portable types ：inttypes.h
intmax_t,uintmax_t,
_Bool type
1 representative true, 2 representative false
Escape sequence
================ Chapter four =================
Strings are stored in character arrays , Each unit is a character , In the end \0 ( Empty character ) end .
scanf() After reading input , In the first white space encountered (blank), Tab (tab) Or line breaks (newline) Stop reading at .
sizeof and strlen() The difference between
sizeof Gives the size of the data in bytes ,strlen() Function gives the length of a string in characters , Specific examples are as follows ：
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