bash$cat printhello.c
#include <stdio.h>
//#include "look.h"

void PrintHello()
{
look();
printf("Hello World\n");
}

bash$cat printbye.c
#include <stdio.h>
//#include "look.h"

void PrintBye()
{
look();
printf("Bye bye\n");
}

bash$ cat look.h
void look();

bash$cat look.c
#include <stdio.h>

void look()
{
printf("Looking\n");
}

bash$gcc printhello.c printbye.c
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
/tmp/cck21S0u.o: In function `PrintHello':
printhello.c:(.text+0x7): undefined reference to `look'
/tmp/ccNWbCnd.o: In function `PrintBye':
printbye.c:(.text+0x7): undefined reference to `look'
collect2: ld returned 1 exit status

bash$gcc -Wall -shared -o libgreet printhello.c printbye.c
printhello.c: In function 'PrintHello':
printhello.c:6: warning: implicit declaration of function 'look'
printbye.c: In function 'PrintBye':
printbye.c:5: warning: implicit declaration of function 'look'

所以我的问题是为什么在链接共享库时符号没有得到解决.当我使用这个库来制作可执行文件时,需要完成这项工作(解析其下游的符号),但这意味着我们需要知道这个库在使用这个库时所依赖的是什么,但这不是不可取的吗？

谢谢,
Jagrati