Imported from /home/lorry/working-area/delta_boost-tarball/boost_1_58_0.tar.bz2.HEADboost_1_58_0master

1 files changed, 75 insertions, 0 deletions

diff --git a/libs/endian/example/endian_example.cpp b/libs/endian/example/endian_example.cpp
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+// endian_example.cpp  -------------------------------------------------------//
+
+//  Copyright Beman Dawes, 2006
+
+//  Distributed under the Boost Software License, Version 1.0.
+//  See http://www.boost.org/LICENSE_1_0.txt
+
+//  See library home page at http://www.boost.org/libs/endian
+
+//----------------------------------------------------------------------------//
+
+#include <boost/endian/detail/disable_warnings.hpp>
+
+#include <iostream>
+#include <cstdio>
+#include <boost/endian/buffers.hpp>
+#include <boost/static_assert.hpp>
+
+using namespace boost::endian;
+
+namespace 
+{
+  //  This is an extract from a very widely used GIS file format. Why the designer
+  //  decided to mix big and little endians in the same file is not known. But
+  //  this is a real-world format and users wishing to write low level code
+  //  manipulating these files have to deal with the mixed endianness.
+
+  struct header
+  {
+    big_int32_buf_at     file_code;
+    big_int32_buf_at     file_length;
+    little_int32_buf_at  version;
+    little_int32_buf_at  shape_type;
+  };
+
+  const char* filename = "test.dat";
+}
+
+int main(int, char* [])
+{
+  header h;
+  
+  BOOST_STATIC_ASSERT(sizeof(h) == 16U);  // reality check
+
+  h.file_code   = 0x01020304;
+  h.file_length = sizeof(header);
+  h.version     = 1;
+  h.shape_type  = 0x01020304;
+
+  //  Low-level I/O such as POSIX read/write or <cstdio> fread/fwrite is sometimes
+  //  used for binary file operations when ultimate efficiency is important.
+  //  Such I/O is often performed in some C++ wrapper class, but to drive home the
+  //  point that endian integers are often used in fairly low-level code that
+  //  does bulk I/O operations, <cstdio> fopen/fwrite is used for I/O in this example.
+
+  std::FILE* fi = std::fopen(filename, "wb");  // MUST BE BINARY
+  
+  if (!fi)
+  {
+    std::cout << "could not open " << filename << '\n';
+    return 1;
+  }
+
+  if (std::fwrite(&h, sizeof(header), 1, fi)!= 1)
+  {
+    std::cout << "write failure for " << filename << '\n';
+    return 1;
+  }
+
+  std::fclose(fi);
+
+  std::cout << "created file " << filename << '\n';
+
+  return 0;
+}