如何将我的C代码链接到PCRE库? (当前引发的链接器错误.) [英] How can I link my C code with the PCRE library? (Linker errors currently being thrown.)

问题描述

注意: 我最初在一个更大的项目中遇到了这个问题；所以我将代码简化为您在下面看到的测试用例.

Note: I originally had this problem in a much larger project; so I pared the code down to the test case you see below.

我不知道如何获取以下测试代码进行编译.具体来说，看起来好像链接器找不到PCRE库(有关如何配置PCRE，请参见下文).而且，尽管将显式的-L/usr/local/lib -lpcre传递给链接器(PCRE安装在/usr/local目录结构中).

I cannot figure out how to get the following test code to compile. Specifically, it appears as if the linker cannot find the PCRE library (see below for how PCRE was configured). And this despite the explicit -L/usr/local/lib -lpcre being passed to the linker (PCRE is installed in the /usr/local directory structure).

我做错了什么? :-(

What am I doing wrong? :-(

控制台输出为:

$ make
rm -f ./*.o
gcc -ansi -Wall -pedantic-errors -I/usr/local/include -g0 -O3 -static -static-libgcc -march=i686 -malign-double -m128bit-long-double -c main.c -o main.o
gcc -ansi -Wall -pedantic-errors -L/usr/local/lib -lpcre -g0 -O3 -static -static-libgcc -march=i686 -malign-double -m128bit-long-double main.o -o pcre_test_1_i686
main.o:main.c:(.text+0x100): undefined reference to `pcre_compile2'
main.o:main.c:(.text+0x12e): undefined reference to `pcre_study'
main.o:main.c:(.text+0x16e): undefined reference to `pcre_exec'
main.o:main.c:(.text+0x19f): undefined reference to `pcre_copy_substring'
collect2: ld returned 1 exit status
make: *** [all] Error 1

---

相关文件

---

PCRE配置和编译环境

---

Relevant Files

---

PCRE Configuration and Compile Environment

./configure --disable-shared --enable-static --disable-cpp --enable-rebuild-chartables --enable-utf8 --enable-unicode-properties --enable-newline-is-any --disable-stack-for-recursion --with-posix-malloc-threshold=2 --with-link-size=4

CC="gcc"
CFLAGS="-g0 -O3 -static -static-libgcc -march=i686 -malign-double -m128bit-long-double"
LD_RUN_PATH="/usr/local/include:/usr/local/lib"

---

main.c

#define PCRE_STATIC  
#include <pcre.h>  
#include <stdlib.h>  
#include <errno.h>  
#include <stdio.h>  
#include <string.h>  

#define OUTPUT_SIZE 12
#define SUBSTRING_SIZE 16

int main(int argc, char *argv[]) {

  pcre *re;
  pcre_extra *extra;
  const char *input = "get food";
  const char *pattern = "^\\s*get\\s+(\\w+)\\s*$\0";
  int options = PCRE_CASELESS | PCRE_UTF8 | PCRE_UCP;
  int error_code = 0;
  int error_offset = 0;
  const char *compile_error;
  const char *study_error;
  int output[OUTPUT_SIZE];
  char substring[SUBSTRING_SIZE];
  int matched = 0;
  int is_error = 0;
  int index = 0;
  for(index = 0; index < OUTPUT_SIZE; index++) {
    output[index] = 0;
  }
  re = pcre_compile2( pattern,
                      options,
                      &error_code,
                      &compile_error,
                      &error_offset,
                      NULL );
  if(re == NULL) {
    fprintf(stderr, "PCRE regular expression error at position %d: %s", error_offset, compile_error);
    exit(EXIT_FAILURE);
  }
  if(error_code == 0) {
    extra = pcre_study( re,
                        0,
                        &study_error );
  }
  else {
    fprintf(stderr, "PCRE regular expression error at position %d: %s", error_offset, compile_error);
    extra = NULL;
  }

  matched = pcre_exec( re,
                       extra,
                       input,
                       (int)strlen(input),
                       0, /* Start at the beginning of the string */
                       0,
                       output,
                       OUTPUT_SIZE );
  if(matched > 1) {
    int status = pcre_copy_substring( input,
                                      output,
                                      matched,
                                      1,
                                      substring,
                                      SUBSTRING_SIZE );
    if(status < 0) {
      switch(status) {
        case PCRE_ERROR_NOMEMORY:
          fprintf(stderr, "PCRE substring extraction error: %s", "Buffer too small");
          break;
        case PCRE_ERROR_NOSUBSTRING:
          fprintf(stderr, "PCRE substring extraction error: %s", "Invalid substring number");
          break;
      }
      is_error = 1;
    }
  }

  printf("Capture group 1 is: '%s'\n", substring);
  if(is_error) {
    printf("There was an error with the pcre_copy_substring() function.\n");
  }

  return EXIT_SUCCESS;
}

---

制作文件

PACKAGE = pcre_test
VERSION = 1

# -ansi == ANSI C
# -std=iso9899:199409 == ANSI C w/ Amendment 1
# -std=c99 == ISO C99
GCC_CMD = gcc -ansi -Wall -pedantic-errors

# Generic: i686
# Intel: core2, corei7, corei7-avx
# AMD: k8-sse3, opteron-sse3, athlon64-sse3, amdfam10
ARCH = i686

RELEASE_FILE = $(PACKAGE)_$(VERSION)_$(ARCH)

GCC_OPTIONS = -g0 -O3 -static -static-libgcc -march=$(ARCH) -malign-double -m128bit-long-double
GCC_COMPILE = $(GCC_CMD) -I/usr/local/include $(GCC_OPTIONS)
GCC_LINK = $(GCC_CMD) -L/usr/local/lib -lpcre $(GCC_OPTIONS)

GCC_LINK_ALL = $(GCC_LINK) main.o

all: clean build_main
        $(GCC_LINK_ALL) -o $(RELEASE_FILE)

build_main:
        $(GCC_COMPILE) -c main.c -o main.o

clean:
        rm -f ./*.o

---

---

所有外部库标志必须在所有目标文件后 列出.因此， Makefile 应该看起来像这样:

All external library flags must be listed after all of the object files. Thus, the Makefile should have looked like this:

GCC_LINK = $(GCC_CMD) -L/usr/local/lib $(GCC_OPTIONS)

GCC_LINK_ALL = $(GCC_LINK) main.o -lpcre

感谢所有回答答案的人. :-)

Thank you to everyone who responded with answers. :-)

推荐答案

链接器是否有可能找到libpcre.so的预构建版本?

Is it possible the linker is finding a pre-built version of the libpcre.so?

尝试使用此问题中的建议: 在编译器命令行上指定/usr/local/lib/libpcre.a ...避免包含-lpcre".

Try the advice from this question: "specify /usr/local/lib/libpcre.a on the compiler command line ... avoid including -lpcre".

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