libpng |建筑的重复符号

Question

我正在尝试在 Mac OS X Yosemite 上使用 libpng 编译一个项目。

我得到了错误：

Undefined symbols for architecture x86_64:
  "_png_create_info_struct", referenced from:
      _writePNG in qrenc.o
  "_png_create_write_struct", referenced from:
      _writePNG in qrenc.o
  "_png_destroy_write_struct", referenced from:
      _writePNG in qrenc.o
  "_png_init_io", referenced from:
      _writePNG in qrenc.o
  "_png_set_IHDR", referenced from:
      _writePNG in qrenc.o
  "_png_set_PLTE", referenced from:
      _writePNG in qrenc.o
  "_png_set_longjmp_fn", referenced from:
      _writePNG in qrenc.o
  "_png_set_pHYs", referenced from:
      _writePNG in qrenc.o
  "_png_set_tRNS", referenced from:
      _writePNG in qrenc.o
  "_png_write_end", referenced from:
      _writePNG in qrenc.o
  "_png_write_info", referenced from:
      _writePNG in qrenc.o
  "_png_write_row", referenced from:
      _writePNG in qrenc.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

所以我在我的 ld 调用中添加了 -lpng。 现在它抛出

duplicate symbol _main in:
    .obj/main.o
    .obj/qrenc.o
ld: 1 duplicate symbol for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

链接自制软件安装的 libpng 时出现同样的错误。

我做错了什么？

Answer 1

您有两个带有 main 函数的文件（可能是 main.c 和 qrenc.c）。从这些文件中删除该函数并使用 -lpng。