Memory unit:
- Byte。1Byte=8bits。
Pointer array and array pointer:
- Pointer array: int* p[n], an array of pointers, storing n addresses;
- Array pointer: int (*p)[n], the pointer of the array, save 1 address.
Structure struct:
- Memory alignment: The memory alignment of the previous variable is an integer multiple of the variable memory behind, and the entire struct is an integer multiple of the maximum variable memory.
Union:
- The same memory location stores different data types, and only one member can have a value at any time. The memory length is determined by the longest member.
so dynamic library and compilation:
- The dynamic library is .dll under windows and .so under linux. The static library is .lib under windows and .a under linux.
- Source files (.h, .cpp, etc.)
- -->Pre-compilation: complete macro replacement, file import, and remove blank lines, comments, etc.
- -->Compile: Process the preprocessed code into assembly code.s. Code inspection, code optimization, assembly code generation.
- -->Assembly: Convert .s to machine code 01 sequence .o file.
- -->Link
- -->Executable file
# 生成目标文件.o
gcc -c test.c
# 生成动态库，-shared代表生成动态库，-fPIC代表使用相对地址
gcc -shared -fPIC -o libtest.so test.o