Reading notes of modern methods of C language programming

The first 2 Chapter C Basic concepts of language

Compile and link

• Preprocessing
• compile
• link

The first 4 Chapter expression

The left value

• Occupy a certain location in computer memory
• It can be placed to the left of the assignment expression

Self increase and self decrease

++i Than i++ The operation is better

The first 7 Chapter Basic types

sizeof Operator

• Gets the number of bytes of the data type
• sizeof Can find the length of the static memory allocation array
• sizeof Can't find the size of dynamically allocated memory

The first 8 Chapter Array

The array subscript

The array subscript is the address offset relative to the first address of the array , Avoid accessing out of bounds when using subscripts to access array elements .

Array initialization

• During array initialization, only the first element can be assigned to 0, The remaining elements in the array are initialized to 0.
• You can define an array without specifying the array size , Determine the size of the array by initializing the number of elements .

The first 12 Chapter Pointers and arrays

Pointers are used for array processing

• Pointers have a way of accessing array elements similar to array names , Use [] Operator to get the array element of the offset relative to the address saved by the pointer .
• You can move the pointer to the end of the array by adding a positive integer to the pointer

The first 14 Chapter The preprocessor

Macro definition

• Instead of global variables
• Eliminate magic number
• It is convenient for program modification , Where the same value is used , Just modify the macro definition
• Macro definitions with parameters use () and do {…} while(0) Protect execution statements
• # Operator can be used to convert the character after the operator into a string ,## Operator can connect the identifiers before and after the operator into an identifier

Conditional compilation

• Debug code blocks using conditional compilation switches , Control the output of debugging information
• Use conditional compilation to protect header files , Avoid multiple inclusion of the same header file

The first 17 Chapter Advanced application of pointer

Assign arrays dynamically

Use malloc Function to allocate dynamic storage space , Need to cooperate with sizeof Operator to calculate the number of bytes of the element of the specified type , And allocate the space of integer multiples .

Free up storage space

• Use free() Function to free dynamically allocated storage space
• The pointer after releasing space needs to be set to NULL, Avoid wild pointers

The first 18 Chapter Statement

static Storage type

• static Declared variables are stored in the static area , Its value is valid throughout the life of the program , It will not be destroyed because of the return of function execution, just like local variables .
• Use static Declarations can make variables and functions visible only in this document , Realization “ encapsulation ” The effect of