Vim
vim filename When on, it is command mode. // filename is opened when it exists, and created and opened when it does not exist gg Is to go directly to the top of the file content, shift + g Directly to the bottom of the file. dd Delete the line where the cursor is located 3dd Delete the line where the cursor is located and the following 2 lines(A total of three lines were deleted) 5G Move the cursor to the fifth line u revoke yy Copy cursor line 3yy Copy the line where the cursor is located and the following 2 lines(A total of three lines are copied) p Paste below the line where the cursor is located P Paste above the line of the cursor \ Find :set nu Yes display line number :set ts=4 Is set tab The key is 4 # You can also write directly to the bottom of sudo vim /etc/vim/vimrc # set ts=4 # set nu knock a Enter write mode, After writing in writing mode, Esc Switch to command mode, then : wq Yes, save and exit vim ; q!Yes exit without saving;
Install gcc
yum install gcc # gcc test.c -o test / / generate an executable file in the current directory / / the - o parameter specifies that the file name of the generated executable file is test, and the default is a.out # ./ test // Execute the generated executable file test
Installation g++
yum install gcc-c++
The following command can save the temporary files left during the compilation process
g++ test.cpp -o test --save-temps # ls -l total 684 -rwx------ 1 root root 17248 Nov 28 17:04 test -rw------- 1 root root 228 Nov 28 16:39 test.cpp -rw------- 1 root root 664410 Nov 28 17:04 test.ii // You can see i file is much larger (664410 bytes) -rw------- 1 root root 2664 Nov 28 17:04 test.o -rw------- 1 root root 2220 Nov 28 17:04 test.s
In the offline state, it needs to be installed in the form of rpm package
For Ubuntu:
sudo apt update sudo apt install build-essential gcc --version gdb --version g++ --version sudo apt install cmake cmake --version
Basic use
gcc commands are called according to different parameters: precompiler (preprocessing and compiling) cc1, assembler as, linker ld
Pretreatment: g++ -E test.cpp // E should be capitalized, preprocessed, and the results are directly output to the terminal. g++ -s test.cpp // An a.out executable file is generated by default compile: g++ -S test.cpp // By default, a test is generated S assembly language file assembly: g++ -c test.s/test.cpp // The default is to generate the machine language test O documentation Equivalent to as test s link: g++ test.o // Generate a.out executable
-g Generation can be gdb Debug information used -O2 Optimize the source code,Make execution more efficient -l Link library file,Followed by the library name -L If the library you want to link is not in(/lib,/usr/lib,/usr/local/lib)In these three directories, You need to specify the directory where the library is located link mytest library, Where is this library/home/bing/mytestlibfolder Directory g++ -L/home/bing/mytestlibfolder -lmytest test.cpp -I If the header file used is not in /usr/include Directory,Just use it -I To specify g++ -I/myinclude test.cpp // The header file used is placed in the / myinclude directory -Wall // Print warning message g++ -Wall test.cpp -std=c++11 Set compilation criteria
nm command, check and analyze the target file, library file and executable file, and analyze the symbol table
Generate static and dynamic libraries
For a custom function io:
Undeclared, undefined, direct use:
error: 'io' was not declared in this scope
Declared but not defined:
undefined reference to `io(char*)' // Reference without definition, illegal
Declare and define the implementation, and the cpp file defining the implementation is compiled together with the main file:
g++ main.cpp hanshu.cpp -o ma ./ma Implemented correctly
Compile it into a target file, and then link it together when linking: (this avoids the compilation process of hanshu.cpp)
g++ hanshu.o main.cpp -o ma ./ma The correct results are also obtained
If there are more than one similar to Hanshu O files are commonly used. If you press the above, you need to add parameters to each.
At this point, you can use the ar tool to package it into a library. A static library is a collection of target files.
ar [-dmpqrtx][cfosSuvV][a<Member file>][b<Member file>][i<Member file>][Library file][Member file] Required parameter: d:Delete the first mock exam in the library t:List the modules included in the stock out r:Insert module into Library,If there is a library with the same name,Replacement occurs q:Insert module into Library,But do not check whether replacement is required x:Extract the module from the library (unzip)
$ ar -t libhanshu.a hanshu.o // View included modules $ ar -q libhanshu.a hanshu.o $ ar -t libhanshu.a hanshu.o // You can see that -q no replacement occurs hanshu.o $ ar -d libhanshu.a hanshu.o // Delete a
g++ main.cpp -lhanshu -L./ -o main // The linked library has also been executed correctly
The advantage is that there is no longer any dependency.
Disadvantages of static libraries:
If the static library is linked by multiple programs, and the static library is bound with the program, there will be multiple copies in memory. In particular, a considerable number of other library functions in the static library are not used, which will cause a great waste of space.
Once a module in the library is updated, the whole program must be recompiled, re linked and then released to the user.
Dynamic library:
The process of linking occurs when the program is running. The dynamic library file is independent of the program using the library.
At this time, the library file is shared. For multiple programs that use the file, there will only be one copy of the library file in memory.
When you want to upgrade a module shared by a program, you only need to overwrite the old target file without reconnecting all programs.
Generate dynamic library:
g++ hanshu.cpp -fPIC -shared -o libhanshu.so // -Shared solves the relocation of shared objects during loading (the modifiable data part in the dynamic link library has multiple copies for different processes) // The instruction part in the fPIC generated address independent code module will not change due to the change of loading address during loading
Link to compile:
$ g++ main.cpp -o main ./libhanshu.so
$ ./main
perhaps
$ g++ main.cpp -o main -lhanshu -L./ // At this time, the default is the linked dynamic library. If there is a duplicate name
$ ./main
At this time, an error will be reported and the library file cannot be found,So you need to specify a path
$ LD_LIBRARY_PATH=./ ./main // So it can run normally
$ ldd main // View dynamic library dependencies for executables
linux-vdso.so.1 (0x00007ffe15bfd000)
./libhanshu.so (0x00007f408442a000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f40840a1000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f4083cb0000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f4083912000)
/lib64/ld-linux-x86-64.so.2 (0x00007f408482e000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f40836fa000)
When the static library and dynamic library have the same name, the dynamic library takes precedence.
Specify a static library:
g++ main.cpp -o main -static -lhanshu -L./
$ ll main main2 8664 12 June 13-17:53 main 2251400 12 June 13-18:14 main2 // You can see that the executable generated through static links is much larger, because many static libraries are bound, but the advantage is that there is no dependency
gdb debugging
g++ tiaoshi.cpp -g -o tiaoshi gdb tiaoshi break 13 # Set a breakpoint on line 13 info breakpoints # View all breakpoint information delete 2 # Delete breakpoint with num 2 run # Start the program and run it to the breakpoint continue # Continue running until the program ends or the next breakpoint is encountered next # Next, do not enter the function step # Next, go inside the function enter # Execute the previous command list Line number # View the source code near this line number print variable # View the value of the variable ptype variable # View the type of variable display variable # You can see the value of the variable at each step of the program. When you don't want to see it, undo num quit # Exit gdb
Installing gcc and g under Linux++
Compiling cpp project with g + + under linux
How to use Tail command in Linux
Hybrid connection of linux dynamic library and static library
The difference between header file and library file
C + + static library and dynamic library
linux -- nm command
nm: file format analysis
nm command details
Powerful file analysis tool under linux - nm
gdb common commands
list usage in gdb