c++ - 如何在 jpeglib.h (jpeg-8c) 中包含 <stdio.h>

Question

我想用 C++ 编辑一些 jpeg 文件。我链接到 libjpg 并编译了我的代码。编译器提示 typedefs FILE 和 size_t。我用谷歌搜索了这个问题，发现这个库是为在 C 而不是 C++ 下编译而设计的，所以我们必须手动将 include stdio.h 添加到“jpeglib.h”。我这样做了，但这次编译器给了我以下错误:

undefined reference to `jpeg_CreateCompress'    JPGImage.cpp    /KFCK/src   line 47 C/C++ Problem
undefined reference to `jpeg_CreateDecompress'  JPGImage.cpp    /KFCK/src   line 92 C/C++ Problem
undefined reference to `jpeg_destroy_compress'  JPGImage.cpp    /KFCK/src   line 77 C/C++ Problem
undefined reference to `jpeg_destroy_decompress'    JPGImage.cpp    /KFCK/src   line 123    C/C++ Problem
undefined reference to `jpeg_finish_compress'   JPGImage.cpp    /KFCK/src   line 74 C/C++ Problem
undefined reference to `jpeg_finish_decompress' JPGImage.cpp    /KFCK/src   line 120    C/C++ Problem
undefined reference to `jpeg_read_header'   JPGImage.cpp    /KFCK/src   line 102    C/C++ Problem
undefined reference to `jpeg_read_scanlines'    JPGImage.cpp    /KFCK/src   line 115    C/C++ Problem
undefined reference to `jpeg_set_defaults'  JPGImage.cpp    /KFCK/src   line 61 C/C++ Problem
undefined reference to `jpeg_set_quality'   JPGImage.cpp    /KFCK/src   line 62 C/C++ Problem
undefined reference to `jpeg_start_compress'    JPGImage.cpp    /KFCK/src   line 65 C/C++ Problem
undefined reference to `jpeg_start_decompress'  JPGImage.cpp    /KFCK/src   line 104    C/C++ Problem

找不到库函数。如果我删除 stdio.h 行并再次编译，我会得到:

‘FILE’ has not been declared    KFCK        line 956, external location: /home/../jpeg-8c/jpeglib.h C/C++ Problem
‘FILE’ has not been declared    KFCK        line 957, external location: /home/../jpeg-8c/jpeglib.h C/C++ Problem
‘size_t’ does not name a type   KFCK        line 756, external location: /home/../jpeg-8c/jpeglib.h C/C++ Problem
‘size_t’ does not name a type   KFCK        line 768, external location: /home/../jpeg-8c/jpeglib.h C/C++ Problem
‘size_t’ has not been declared  KFCK        line 799, external location: /home/../jpeg-

我该怎么办？

Answer 1

把#include 放回去。但是看起来很像你在链接时没有添加 -ljpeg 或类似的东西。此外，您还需要确保如果将其包含在 C++ 代码中，您可能需要执行以下操作:

extern "C" {
#include <jpeglib.h>
}