C program without title

Question

I am writing a program "hello world" in C.

void main()
{ printf("Hello World"); }
// note that I haven't included any header file

The program compiles with a warning like

vikram@vikram-Studio-XPS-1645:~$ gcc hello.c 
hello.c: In function ‘main’:
hello.c:2:2: warning: incompatible implicit declaration of built-in function ‘printf’
vikram@vikram-Studio-XPS-1645:~$ ./a.out 
Hello Worldvikram@vikram-Studio-XPS-1645:~$

How is this possible? How does the OS link the library without including any header?

Answer 1

The compiler creates your source file with a link to a function with a name printf(), not knowing what arguments it actually takes or what its return type is. The generated assembly contains pushline addresses "Hello World"in the static data area of ​​your program, and then callto printf.

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Answer 2

printf C (libc ), ( gcc printf, ).

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Answer 3

C, , , ​​. printf stdio.h.

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extern int foo();

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Answer 4

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Answer 5

hello.c: 2: 2: : 'printf

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