C/C++

ldd : list library

LD_LIBRARY_PATH = "List all dynamic library"

https://scrapbox.io/files/66d0452060f13c001c823ab3.png

Static gives smaller docker

https://scrapbox.io/files/66d045c19faba4001cf23673.png

C

Header only have prototype of function

code:minimal.c

int main(){

return 0;

}

Any program need to have a return int to give information on how the process terminated.

code:with_exit.c

int main() {

exit(0); // return error, but doesn't clean memory stack e.g

}

gcc -o test -DMONDEFINE=1 test.c

code:with_exit.c

int main(){

return MONDEFINE; // return error, but doesn't clean memory stack e.g

}

Some Assembly

code:some_asm.c

int geteax() {

__asm__("mov eax,42;");

}

int main(){

return geteax();

}

gcc -o out -masm=intel out.c

clang vs gcc , different implementation, clang faster at compile time .

clan -m32 -g -o output input.c

32 bits , debug symbol

code:.sh

lldb

b main

r

s # step

p sizeof(i) # size of variable i

p &i # adress of i

p i # val of i

x/4b &i # Examine adress : 4 byte at i adress

0x00 0x04 0x00 0x00 << 1024 = 0x400

Initialisation of variable not guaranteeted to be Zeroed

When a process get created, we got some part of memory allocated.

little endian

C++

g++

-g : Ajoute info de debug

-Wall : Tous les warnings

Header

Namespace

io

fprinf(stdout, "Hello World!\n");

ou

std::cout << "Hello world!" << std::endl;