makefile 中未定义对“func”错误的引用答案

【问题标题】：undefined reference to 'func' error in makefilemakefile 中未定义对“func”错误的引用
【发布时间】：2018-08-18 12:10:54
【问题描述】：

我试图将引用从一个头文件传递到我的主文件，当这些函数写在不同的 .c 文件中时，我得到一个undefined reference to 'fund' 到所有这些函数。在我的主文件中，当#include "Declerations.h" 代码为时，我只有一个包含#include "Declerations.h"：

#ifndef Declerations_h
#define  Declerations_h
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "Machine_Memory.h"
#include "Symbols.h"

#define MAX_LINE 1024
#define A 0
#define R 2
#define E 1
#define RIGHT_BIT 16384
#define BITS_IN_WORD 14

int is_a_op(char * wrd);
int find_op(char *wrd);
int op_group(int op);
int is_a_sign(char * wrd);
int is_new_line(char * wrd);
#endif

制作文件：

assembler: Assembler.o DecleratioFuncs.o SymbolFuncs.o
    gcc -g -ansi -Wall -pedantic Assembler.o SymbolFuncs.o DecleratioFuncs.o -o assembler
Assembler.o: Assembler.c Declerations.h
    gcc -c -ansi -Wall -pedantic -o Assembler.o Assembler.c
SymbolFuncs.o: SymbolFuncs.c Declerations.h
    gcc -c -ansi -Wall -pedantic -o SymbolFuncs.o SymbolFuncs.c
DecleratioFuncs.o: DecleratioFuncs.c Declerations.h
    gcc -c -ansi -pedantic -Wall -o DecleratioFuncs.o DecleratioFuncs.c

我没有得到SymbolFuncs.c 和DecleratioFuncs.c 函数，并且在Assembler.c 中得到相同的错误。另请注意，SymbolFuncs 函数在Symbols.h 中声明发生错误的输出窗口部分：

student@ubuntu:~/Desktop/Finished_Project$ make
gcc -ansi -Wall -pedantic -o Assembler.o Assembler.c
Assembler.c: In function ‘main’:
Assembler.c:28:2: warning: ISO C90 forbids mixed declarations and code [-pedantic]
Assembler.c:243:9: warning: format ‘%s’ expects argument of type ‘char *’, but argument 2 has type ‘int’ [-Wformat]
Assembler.c:268:6: warning: format ‘%d’ expects a matching ‘int’ argument [-Wformat]
Assembler.c:317:9: warning: value computed is not used [-Wunused-value]
Assembler.c:342:9: warning: value computed is not used [-Wunused-value]
Assembler.c:376:19: warning: comparison with string literal results in unspecified behavior [-Waddress]
Assembler.c:392:8: warning: value computed is not used [-Wunused-value]
Assembler.c:424:8: warning: value computed is not used [-Wunused-value]
Assembler.c:447:9: warning: value computed is not used [-Wunused-value]
Assembler.c:464:9: warning: value computed is not used [-Wunused-value]
Assembler.c:500:8: warning: value computed is not used [-Wunused-value]
Assembler.c:548:8: warning: value computed is not used [-Wunused-value]
Assembler.c:581:8: warning: value computed is not used [-Wunused-value]
Assembler.c:602:9: warning: value computed is not used [-Wunused-value]
Assembler.c:648:8: warning: value computed is not used [-Wunused-value]
Assembler.c:58:37: warning: unused variable ‘entry_list’ [-Wunused-variable]
Assembler.c:58:16: warning: unused variable ‘extern_list’ [-Wunused-variable]
Assembler.c:51:18: warning: unused variable ‘num_to_add’ [-Wunused-variable]
Assembler.c:46:6: warning: variable ‘L’ set but not used [-Wunused-but-set-variable]
Assembler.c:42:6: warning: unused variable ‘ise’ [-Wunused-variable]
Assembler.c:33:33: warning: unused variable ‘next’ [-Wunused-variable]
Assembler.c:33:17: warning: unused variable ‘memory’ [-Wunused-variable]
Assembler.c: In function ‘add_to_mem’:
Assembler.c:757:2: warning: ISO C90 forbids mixed declarations and code [-pedantic]
Assembler.c:767:2: warning: ISO C90 forbids mixed declarations and code [-pedantic]
Assembler.c:767:6: warning: unused variable ‘val’ [-Wunused-variable]
/tmp/ccdCytpY.o: In function `main':
Assembler.c:(.text+0x171): undefined reference to `is_new_line'
Assembler.c:(.text+0x18c): undefined reference to `is_a_sign'
Assembler.c:(.text+0x278): undefined reference to `add_to_slist'
Assembler.c:(.text+0x785): undefined reference to `find_op'
Assembler.c:(.text+0x853): undefined reference to `op_group'
Assembler.c:(.text+0x897): undefined reference to `is_a_sign'
Assembler.c:(.text+0x981): undefined reference to `is_a_sign'
Assembler.c:(.text+0xa88): undefined reference to `op_group'
Assembler.c:(.text+0xc2a): undefined reference to `is_a_sign'
Assembler.c:(.text+0xcc9): undefined reference to `is_a_sign'
Assembler.c:(.text+0x103d): undefined reference to `is_a_sign'
Assembler.c:(.text+0x109b): undefined reference to `op_group'
Assembler.c:(.text+0x11e2): undefined reference to `is_a_sign'
Assembler.c:(.text+0x14c3): undefined reference to `is_a_sign'
Assembler.c:(.text+0x16dc): undefined reference to `find_address'
collect2: ld returned 1 exit status
make: *** [Assembler.o] Error 1

【问题讨论】：

你的makefile是否有依赖DecleratioFuncs.o: DecleratioFuncs.o？
我刚刚注意到是DecleratioFuncs.o: DecleratioFuncs.o而不是ecleratioFuncs.o: DecleratioFuncs.c，我把它改成了ecleratioFuncs.o: DecleratioFuncs.c`，问题还是一样。
您可以删除 .o 文件的规则：只需使用变量 CC=gcc 和 CFLAGS=-ansi -Wall -pedantic 设置正确的编译器标志。但是，这应该与您的问题无关。你能显示所有的“make”输出（尤其是命令运行）
@Yunnosch 这甚至可能是他的问题的原因；如果DeclaratioFuncs.o是在以前的版本中编译的，没有错误消息中的函数，即使DeclaratioFuncs.c被改变也不会重新编译。
@Ctx 我用新的 makefile 代码和完整的输出窗口编辑了帖子。而且我认为这与问题无关，只是语义

标签： c makefile header undefined

【解决方案1】：

您在输出中看到：

gcc -ansi -Wall -pedantic -o Assembler.o Assembler.c

这里缺少编译器标志-c，所以它正在尝试链接，这当然失败了。

但是，根据您的 makefile 中的规则，这不应该发生。可能还有第二个 Makefile（大写 M，优先于小写 m 的 makefile）具有不同的规则。你应该删除它。

【讨论】：