我一直试图找出为什么当gcc尝试将目标文件链接在一起时，我收到此特定错误的原因：
Undefined first referenced
symbol in file
main /usr/local/gcc_4.7.1/lib/gcc/sparc-sun-solaris2.10/4.7.1/crt1.o
ld: fatal: symbol referencing errors. No output written to complex
collect2: error: ld returned 1 exit status
调用您正在查看的代码以供使用。目的是能够理解makefile并在gcc上将所有这些文件链接在一起。我相信问题来自makefile或main.c.请帮助我一直试图纠正这几个小时。我一直在使用的命令是：
make makefile
gcc complex.c -o complex -lm
我已经彻底搜索了网络，找到导致这种情况的原因，但对我来说没有任何意义。下面我将把我试图链接在一起的三个文件放在一起：complex.c，main.c complex.h和我的makefile。
complex.c里：
// Figure 11.10 Partial Implementation of Type and Operators for Complex Numbers
/*
* Operators to process complex numbers
*/
/* User-defined complex number type */
#include <stdio.h>
#include <math.h>
#include "complex.h"
/*
* Complex number input function returns standard scanning error code
* 1 => valid scan, 0 => error, negative EOF value => end of file
*/
int
scan_complex(complex_t *c) /* output - address of complex variable to
fill */
{
int status;
status = scanf("%lf%lf", &c->real, &c->imag);
if (status == 2)
status = 1;
else if (status != EOF)
status = 0;
return (status);
}
/*
* Complex output function displays value as (a + bi) or (a - bi),
* dropping a or b if they round to 0 unless both round to 0
*/
void
print_complex(complex_t c) /* input - complex number to display */
{
double a, b;
char sign;
a = c.real;
b = c.imag;
printf("(");
if (fabs(a) < .005 && fabs(b) < .005) {
printf("%.2f", 0.0);
} else if (fabs(b) < .005) {
printf("%.2f", a);
} else if (fabs(a) < .005) {
printf("%.2fi", b);
} else {
if (b < 0)
sign = '-';
else
sign = '+';
printf("%.2f %c %.2fi", a, sign, fabs(b));
}
printf(")");
}
/*
* Returns sum of complex values c1 and c2
*/
complex_t
add_complex(complex_t c1, complex_t c2) /* input - values to add */
{
complex_t csum;
csum.real = c1.real + c2.real;
csum.imag = c1.imag + c2.imag;
return (csum);
}
/*
* Returns difference c1 - c2
*/
complex_t
subtract_complex(complex_t c1, complex_t c2) /* input parameters */
{
complex_t cdiff;
cdiff.real = c1.real - c2.real;
cdiff.imag = c1.imag - c2.imag;
return (cdiff);
}
/* ** Stub **
* Returns product of complex values c1 and c2
*/
complex_t
multiply_complex(complex_t c1, complex_t c2) /* input parameters */
{
complex_t cmul;
double a, b, c, d;
a = c1.real;
b = c1.imag;
c = c2.real;
d = c2.imag;
if (( b > 0 && d < 0) || (b < 0 && d > 0))
{
cmul.real - (a*c) + (fabs(b)*fabs(d));
cmul.imag = (a*d) + (b*c);
}
else if (( b>0 && d>0) || (b<0 && d<0))
{
cmul.real = (a*c) - (b*d);
cmul.imag = (a*d) + (b*c);
}
return (cmul);
}
/* ** Stub **
* Returns quotient of complex values (c1 / c2)
*/
complex_t
divide_complex(complex_t c1, complex_t c2) /* input parameters */
{
complex_t cdiv;
double a, b, c, d;
a = c1.real;
b = c1.imag;
c = c2.real;
d = c2.imag;
if ( b > 0 && d < 0)
{
cdiv.real = (a*c) - (fabs(b)*fabs(d)) / ((c*c) + (d*d));
cdiv.imag = (a*d) + (b*c) / ((c*c) + (d*d));
}
else if ( b>0 && d>0)
{
cdiv.real = (a*c) - (fabs(b)*fabs(d)) / ((c*c) + (d*d));
cdiv.imag = ((-1*a*d) + (b*c)) / ((c*c) + (d*d));
}
else if (b<0 && d<0)
{
cdiv.real = (a*c) + (fabs(b)*fabs(d)) / ((c*c) + (d*d));
cdiv.imag = ((-1*a*d) + (b*c)) / ((c*c) + (d*d));
}
else if (b<0 && d<0)
{
cdiv.real = (a*c) + (fabs(b)*fabs(d)) / ((c*c) + (d*d));
cdiv.imag = ((a*fabs(d)) + (b*c)) / ((c*c) + (d*d));
}
return (cdiv);
}
/*
* Returns absolute value of complex number c
*/
complex_t
abs_complex(complex_t c) /* input parameter */
{
complex_t cabs;
cabs.real = sqrt(c.real * c.real + c.imag * c.imag);
cabs.imag = 0;
return (cabs);
}
的main.c
#include <stdio.h>
#include "complex.h"
int main (void)
{
complex_t com1, com2;
/* Gets two complex numbers */
printf("Enter the real and imaginary parts of a complex number\n");
printf("separated by a space> ");
scan_complex(&com1);
printf("Enter a second complex number> ");
scan_complex(&com2);
/* Forms and displays the sum */
printf("\n");
print_complex(com1);
printf(" + ");
print_complex(com2);
printf(" = ");
print_complex(add_complex(com1, com2));
/* Forms and displays the difference */
printf("\n\n");
print_complex(com1);
printf(" - ");
print_complex(com2);
printf(" = ");
print_complex(subtract_complex(com1, com2));
/* Forms and displays the multiplication */
printf("\n");
print_complex(com1);
printf(" * ");
print_complex(com2);
printf(" = ");
print_complex(multiply_complex(com1, com2));
/* Forms and displays the division */
printf("\n");
print_complex(com1);
printf(" / ");
print_complex(com2);
printf(" = ");
print_complex(divide_complex(com1, com2));
/* Forms and displays the absolute value of the first number */
printf("\n\n|");
print_complex(com1);
printf("| = ");
print_complex(abs_complex(com1));
printf("\n");
return (0);
}
complex.h：
typedef struct {
double real, imag;
} complex_t;
int scan_complex(complex_t *c);
void print_complex(complex_t c);
complex_t add_complex(complex_t c1, complex_t c2);
complex_t subtract_complex(complex_t c1, complex_t c2);
complex_t multiply_complex(complex_t c1, complex_t c2);
complex_t divide_complex(complex_t c1, complex_t c2);
complex_t abs_complex(complex_t c);
生成文件：
complex: main.o complex.o
gcc -o complex main.o complex.o -lm
main.o: complex.h
gcc -c main.c
complex.o: complex.h
gcc -c complex.c
答案 0 :(得分：2)
只需输入make
更传统的是拼写主制作文件“Makefile”（大写M）。
如果要将makefile命名为Makefile.common之类的其他内容，例如，您需要使用-f选项明确指定：例如： make -f Makefile.com
我认为make文件本身没有任何问题。
答案 1 :(得分：2)
您无需运行gcc命令，只需make。即。
$ make
$ ./complex
使用你的gcc命令，你试图将complex.c分别编译成二进制可执行文件，这当然不起作用，因为它没有主函数。
如果要直接使用gcc编译二进制文件，只需包含两个源文件：
$ gcc -o complex main.c complex.c -lm