- 论坛徽章:
- 0
|
原帖由 MMMIX 于 2007-4-16 16:53 发表
把具体的代码贴出来,要完整的。如果贴正式代码不方便,就给个完整的例子。
代码太烦琐,牵涉的头文件太多了
我再具体描述下吧:
我的系统是32位的red hat as4
我用cc -D_FILE_OFFSET_BITS=64编译了代码,生成了一个大于2G的数据文件,里面存放的是结构体数据,每条数据占的空间相同(76字节)
我用fseeko函数定位后,gdb结果显示:
435 fseeko(fp,offset,SEEK_CUR);
(gdb) p offset
$4 = 2279999924/*超过2g了*/
查看fseeko后的fp
gdb结果显示:
(gdb) p *fp
$6 = {_flags = -72539000, _IO_read_ptr = 0xb7ffd004 "S", _IO_read_end = 0xb7ffe000 "30000010\n70412.dat\n", _IO_read_base = 0xb7ffd000 "\026\a\"\002S",
_IO_write_base = 0xb7ffd000 "\026\a\"\002S", _IO_write_ptr = 0xb7ffd000 "\026\a\"\002S", _IO_write_end = 0xb7ffd000 "\026\a\"\002S",
_IO_buf_base = 0xb7ffd000 "\026\a\"\002S", _IO_buf_end = 0xb7ffe000 "30000010\n70412.dat\n", _IO_save_base = 0x0, _IO_backup_base = 0x0, _IO_save_end = 0x0, _markers = 0x0,
_chain = 0x29f480, _fileno = 6, _flags2 = 0, _old_offset = 0, _cur_column = 0, _vtable_offset = 0 '\0', _shortbuf = "", _lock = 0x9e9f0a0, _offset = -1, __pad1 = 0x0,
__pad2 = 0x9e9f0ac, _mode = -1, _unused2 = '\0' <repeats 51 times>}
查看fread后读到的第一个记录:
(gdb) n
437 for(i=0;i<(testNumber+1);i++)
(gdb) n
439 memset(&tradeInfo,0,sizeof(CQMemoryRecord));
(gdb) n
440 rc=fread(&tradeInfo,sizeof(CQMemoryRecord),1,fp);
(gdb) n
441 if(rc<0)
(gdb) p tradeInfo
$7 = {cBS = 83 'S', lCJBH = 1, sGSDM = "20136", lCJSL = 6736500, lLOTSIZE = 1, sZQDM = "600030", lSBSJ = 93020, lCJSJ = 93020, lCJJG = 27106, lBCYE = 0, sMJBH = " ",
sSQBH = "Qq12345689 ", sGDDM = ' ' <repeats 11 times>}
(gdb)
里面的lCJBH=1表示是文件中的第一条记录,也就是说我读到了文件开始的地方 |
|