C语言编译过程

#include <stdio.h>
#include "head.h"
/*
annotation one
annotation two
*/
extern int N;
int main(){
    printf("build test N=%d\n",N);
    printStr("abc");
    getchar();
}

#ifndef HEAD_H
#define HEAD_H
int N=100;
void printStr(char *);
#endif

#include<stdio.h>
void printStr(char *str){
    printf("%s\n",str);
}

...省略部分代码
# 2 "a.c" 2
# 1 "head.h" 1



# 3 "head.h"
int N=100;
void printStr(char *);
# 3 "a.c" 2




extern int N;
int main(){
 printf("build test N=%d\n",N);
 printStr("abc");
 getchar();
}

    .file   "a.c"
    .globl  _N
    .data
    .align 4
_N:
    .long   100
    .def    ___main;    .scl    2;  .type   32; .endef
    .section .rdata,"dr"
LC0:
    .ascii "build test N=%d\12\0"
LC1:
    .ascii "abc\0"
    .text
    .globl  _main
    .def    _main;  .scl    2;  .type   32; .endef
_main:
LFB10:
    .cfi_startproc
    pushl   %ebp
    .cfi_def_cfa_offset 8
    .cfi_offset 5, -8
    movl    %esp, %ebp
    .cfi_def_cfa_register 5
    andl    $-16, %esp
    subl    $16, %esp
    call    ___main
    movl    _N, %eax
    movl    %eax, 4(%esp)
    movl    $LC0, (%esp)
    call    _printf
    movl    $LC1, (%esp)
    call    _printStr
    call    _getchar
    movl    $0, %eax
    leave
    .cfi_restore 5
    .cfi_def_cfa 4, 4
    ret
    .cfi_endproc
LFE10:
    .ident  "GCC: (GNU) 5.3.0"
    .def    _printf;    .scl    2;  .type   32; .endef
    .def    _printStr;  .scl    2;  .type   32; .endef
    .def    _getchar;   .scl    2;  .type   32; .endef

说下生成静态库的方法：  
    ar cr libxxx.a file1.o file2.o  
就是把file1.o和file2.o打包生成libxxx.a静态库  
使用的时候  
    gcc test.c -L/path -lxxx -o test  
  
动态库的话：  
    gcc -fPIC -shared file1.c -o libxxx.so  
也可以分成两部来写：  
    gcc -fPIC file1.c -c //这一步生成file1.o  
    gcc -shared file1.o -o libtest.so