(.text+0x20): 对“main"的未定义引用和对函数的未定义引用 [英] (.text+0x20): undefined reference to `main' and undefined reference to function

问题描述

我在让我的 makefile 正常工作时遇到问题.我遇到的第一个问题是对 main 的未定义引用.我的 producer.c 文件中有 main 作为函数.第二个问题是对 SearchCustomer() 的未定义引用.

I am having issue getting my makefile to work without errors. The first issue i have is with an undefined reference to main. I have main in my producer.c file as a function. The second issue is an undefined reference to SearchCustomer().

错误:

bash-4.1$ make
gcc -Wall -c producer.c shared.h
gcc -Wall -c consumer.c shared.h
gcc -Wall -c AddRemove.c shared.h
gcc -pthread -Wall -o producer.o consumer.o AddRemove.o
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
AddRemove.o: In function `AddRemove':
AddRemove.c:(.text+0xb1): undefined reference to `SearchCustomer'
AddRemove.c:(.text+0x1e9): undefined reference to `SearchCustomer'
AddRemove.c:(.text+0x351): undefined reference to `SearchCustomer'
collect2: ld returned 1 exit status
make: *** [producer] Error 1

制作文件:

COMPILER = gcc
CCFLAGS = -Wall
all: main

debug:
    make DEBUG=TRUE


main: producer.o consumer.o AddRemove.o
    $(COMPILER) -pthread $(CCFLAGS) -o producer.o consumer.o AddRemove.o
producer.o: producer.c shared.h
    $(COMPILER) $(CCFLAGS) -c producer.c shared.h
consumer.o: consumer.c shared.h
    $(COMPILER) $(CCFLAGS) -c consumer.c shared.h
AddRemove.o: AddRemove.c shared.h
    $(COMPILER) $(CCFLAGS) -c AddRemove.c shared.h


ifeq ($(DEBUG), TRUE)
    CCFLAGS += -g
endif

clean:
    rm -f *.o

推荐答案

此规则

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o producer.o consumer.o AddRemove.o

错了.它说要创建一个名为 producer.o 的文件(使用 -o producer.o)，但您想要创建一个名为 main 的文件.请原谅大喊大叫，但始终使用 $@ 来引用目标:

is wrong. It says to create a file named producer.o (with -o producer.o), but you want to create a file named main. Please excuse the shouting, but ALWAYS USE $@ TO REFERENCE THE TARGET:

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o $@ producer.o consumer.o AddRemove.o

正如 Shahbaz 正确指出的那样，gmake 专业人员也会使用 $^，它扩展到规则中的所有先决条件.一般来说，如果您发现自己重复了一个字符串或名称，那么您就做错了，应该使用一个变量，无论是内置变量之一还是您创建的变量.

As Shahbaz rightly points out, the gmake professionals would also use $^ which expands to all the prerequisites in the rule. In general, if you find yourself repeating a string or name, you're doing it wrong and should use a variable, whether one of the built-ins or one you create.

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o $@ $^

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