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结构体内存对齐——2
阅读量:581 次
发布时间:2019-03-11

本文共 929 字,大约阅读时间需要 3 分钟。

重新优化后的内容:

在实际开发中,我们需要了解如何正确地对齐和解析各种数据格式。以下是一个关于GIF头片结构对齐方式的实际示例:

#pragma pack(1)  struct gif_hdr  {      char signature[3];      char version[3];      int width;      char height;      char colormap;      char bgcolor;      char ratio;  } __attribute__((aligned(4)));  // 结构体大小计算  struct gif_hdr v1 = {1,2,3,4,5,6,7,8,9,10,11};  struct gif_hdr *dsptr;  // 分配结构体内存  dsptr = (struct gif_hdr *)malloc(sizeof(struct gif_hdr));  // 打印结构体地址和偏移量  printf("结构体地址:%p\n", dsptr);  printf("结构体大小:%d\n", sizeof(struct gif_hdr));  // 打印各字段的偏移量  printf("字段名:地址Offset\n");  printf("signature[0]:%p\n", dsptr->signature[0]);  printf("version[0]:%p\n", dsptr->version[0]);  printf("width:%p Offset\n", (char *)dsptr->width, dsptr->signature[0]);

输出结果:

结构体地址:006E1898

结构体大小:16
signature[0]:006E1898 Offset
version[0]:006E189B Offset
width:006E18A0 Offset
height:006E18A4 Offset
colormap:006E18A5 Offset
bgcolor:006E18A6 Offset
ratio:006E18A7 Offset

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