寻求问题 [英] problem with seekg
问题描述
我在我的程序中使用的函数出现问题
从''命令文件'中读取句子并解析它们进入命令。
令人惊讶的是，该程序在某些计算机上工作正常，而在其他计算机上则不然。我试过调试，无法理解它。我将
缩小到了seekg函数并制作了这个简单的程序
（据我所知）似乎没有按预期在所有
到目前为止我试过的电脑。
如果我出错了请告诉我...
#include< iostream> ;
#include< fstream>
使用命名空间std;
int _tmain（int argc，_TCHAR * argv [] ）
{
ifstream是（test.txt）;
char test [256];
是> test;
cout<<测试<< endl;
is.seekg（-2，ios :: cur）;
是> test;
cout<<测试<< endl;
返回0;
}
这里是test.txt的不同版本及其相应的输出
在所有情况下，我预计输出将是
createModel
el
我做错了什么？
案例1：test.txt的内容：
createModel
输出：
createModel
del
案例2：test.txt的内容
createModel
测试
/ *
* /
输出：
createModel
eModel
案例3：test.txt的内容：
createModel
测试
/ *
* /
CreateElements
196
DMElasticElement
0 195 1
-1
exitCreateElements
输出：
createModel
谢谢
Julian。
Julian写道：
我在我的程序中使用的函数出现问题
读句子从''命令文件''并将它们解析为命令。
令人惊讶的是，该程序在某些计算机上工作正常，而在其他计算机上则不然。我试过调试，无法理解它。我将
缩小到了seekg函数并制作了这个简单的程序
（据我所知）似乎没有按预期在所有
到目前为止我试过的电脑。
如果我出错了请告诉我...
#include< iostream> ;
#include< fstream>
使用命名空间std;
int _tmain（int argc，_TCHAR * argv [] ）
{
ifstream是（test.txt）;
char test [256];
test [0] = 0;
是> test;
cout<<测试<< endl;
is.seekg（-2，ios :: cur）;
test [0] = 0;
是> test;
cout<<测试<< endl;
返回0;
}
这里是test.txt的不同版本及其相应的输出
在所有情况下，我预计输出将是
createModel
el
我做错了什么？
案例1：test.txt的内容：
createModel
输出：
createModel
del
案例2：test.txt的内容
createModel
测试
/ *
* /
输出：
createModel
eModel
案例3：test.txt的内容：
createModel
测试
/ *
* /
CreateElements
196
DMElasticElement
0 195 1
-1
exitCreateElements
输出：
createModel
谢谢
朱利安。
记得考虑（看不见）
向后搜索$&b
每行末尾的换行符号（&\\; \\\在Windows上，\ n>
在unix / linux上，" \ r"在Mac上（？））。
如果''test.txt''只有一行，则必须以换行符结尾;
否则结果不像预期的那样。例如for Windows：
createModel \\ n
c
" Larry Smith" ; < ls **** @ nospam.comwrote in message
news：yzCOh.26810
xE.11979@trnddc08 ...
< blockquote class =post_quotes>
Julian写道：
>
我遇到的问题我一直在使用在我的程序中
从''命令文件'中读取句子并将其解析为命令。令人惊讶的是，该程序在某些计算机上运行良好，而在其他计算机上则不然。我试过调试，无法理解它。我把它缩小到了seekg函数并制作了这个简单的程序
（根据我的理解）似乎没有像我预期的那样在所有的计算机中工作到目前为止尝试了。
如果我出错了，请告诉我。
#include< iostream>
#include< fstream>
使用namespace std;
int _tmain（int argc，_TCHAR * argv []）
{if / ifstream是（test.txt）;
char test [ 256];
test [0] = 0;
>是> test;
cout<<测试<< endl;
is.seekg（-2，ios :: cur）;
test [0] = 0;
>是> test;
cout<<测试<< endl;
返回0;
}
这里有不同版本的test.txt及其相应的
输出
在我预期的所有情况下输出将是
createModel
我在做错了什么？
案例1：test.txt的内容：
createModel
输出：
createModel
del
案例2：test.txt的内容
createModel
测试
/ *
* /
输出：
createModel
eModel
案例3：test.txt的内容：
createModel
测试 / *
* /
CreateElements
196
DMElasticElement
0 195 1
-1
exitCreateElements
输出：
createModel
感谢
朱利安。
记得考虑（看不见）
每行结束时
换行符号
向后搜索（在Windows上为\\\\ nn，\ n"
unix / linux上的
，Mac上的\ r（？））。
如果''test.txt''只有一行，则必须以换行结束;
否则结果不符合预期。例如对于Windows：
createModel \\\\ n
感谢回复...但我是不确定这是否解释了一切。即使
如果我需要考虑隐形角色，结果也不会产生
感觉......我尝试了各种组合..但它似乎它正在寻求超过2个补偿，但是我刚刚要求偏移2.如果我认为
这个不可见的字符，它应该有效地仅偏移1个可见
字符......相反它是抵消3
另一个问题：为什么结果随着
文件中的行数而变化？ ...即使我只是在读第一行！
我拥有的行数越多，抵消的就越多。
Hi,
I am having problems with a function that I have been using in my program to
read sentences from a ''command file'' and parse them into commands. the
surprising thing is that the program works fine on some computers and not so
fine on others. I tried debugging and cannot make any sense of it. I
narrowed it down to the seekg function and made this simple program which
(from what I understand) does not seem to be working as expected in all the
computers I have tried so far.
please let me know if I have got something wrong...
#include <iostream>
#include <fstream>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
ifstream is("test.txt");
char test[256];
is >test;
cout << test << endl;
is.seekg(-2,ios::cur);
is >test;
cout << test << endl;
return 0;
}
here are the different versions of test.txt and their corresponding outputs
in all the cases I expected that the output would be
createModel
el
what am I doing wrong ?
case 1: contents of test.txt :
createModel
OUTPUT:
createModel
del
case 2: contents of test.txt
createModel
testing
/*
*/
OUTPUT:
createModel
eModel
case 3: contents of test.txt :
createModel
testing
/*
*/
CreateElements
196
DMElasticElement
0 195 1
-1
exitCreateElements
OUTPUT:
createModel
thanks
Julian.
Julian wrote:Hi,
I am having problems with a function that I have been using in my program to
read sentences from a ''command file'' and parse them into commands. the
surprising thing is that the program works fine on some computers and not so
fine on others. I tried debugging and cannot make any sense of it. I
narrowed it down to the seekg function and made this simple program which
(from what I understand) does not seem to be working as expected in all the
computers I have tried so far.
please let me know if I have got something wrong...
#include <iostream>
#include <fstream>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
ifstream is("test.txt");
char test[256];test[0] = 0;
is >test;
cout << test << endl;
is.seekg(-2,ios::cur);test[0] = 0;
is >test;
cout << test << endl;
return 0;
}
here are the different versions of test.txt and their corresponding outputs
in all the cases I expected that the output would be
createModel
el
what am I doing wrong ?
case 1: contents of test.txt :
createModel
OUTPUT:
createModel
del
case 2: contents of test.txt
createModel
testing
/*
*/
OUTPUT:
createModel
eModel
case 3: contents of test.txt :
createModel
testing
/*
*/
CreateElements
196
DMElasticElement
0 195 1
-1
exitCreateElements
OUTPUT:
createModel
thanks
Julian.
Remember to account for the (invisible)
newline chars at the end of each line when
seeking backwards ("\r\n" on Windows, "\n"
on unix/linux, "\r" on Mac(?) ).
If ''test.txt'' has just one line, it must end with a newline;
otherwise the result is not as expected. e.g. for Windows:
createModel\r\n
c
"Larry Smith" <ls****@nospam.comwrote in message
news:yzCOh.26810
xE.11979@trnddc08...Julian wrote:>Hi,
I am having problems with a function that I have been using in my program
to
read sentences from a ''command file'' and parse them into commands. the
surprising thing is that the program works fine on some computers and not
so
fine on others. I tried debugging and cannot make any sense of it. I
narrowed it down to the seekg function and made this simple program which
(from what I understand) does not seem to be working as expected in all
the
computers I have tried so far.
please let me know if I have got something wrong...
#include <iostream>
#include <fstream>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
ifstream is("test.txt");
char test[256];
test[0] = 0;
>is >test;
cout << test << endl;
is.seekg(-2,ios::cur);
test[0] = 0;
>is >test;
cout << test << endl;
return 0;
}
here are the different versions of test.txt and their corresponding
outputs
in all the cases I expected that the output would be
createModel
el
what am I doing wrong ?
case 1: contents of test.txt :
createModel
OUTPUT:
createModel
del
case 2: contents of test.txt
createModel
testing
/*
*/
OUTPUT:
createModel
eModel
case 3: contents of test.txt :
createModel
testing
/*
*/
CreateElements
196
DMElasticElement
0 195 1
-1
exitCreateElements
OUTPUT:
createModel
thanks
Julian.
Remember to account for the (invisible)
newline chars at the end of each line when
seeking backwards ("\r\n" on Windows, "\n"
on unix/linux, "\r" on Mac(?) ).
If ''test.txt'' has just one line, it must end with a newline;
otherwise the result is not as expected. e.g. for Windows:
createModel\r\nthanks for the reply... but I''m not sure if that explains everything. even
if I need to account for the invisible characters, the results don''t make
sense... I tried all kinds of combinations.. but it seems like it is seeking
more than 2 offsets although I have just asked to offset 2. if I account for
the invisible characters, it should effectively offset only 1 visible
character... instead it is offsetting 3
another problem: why does the result change with the number of lines in the
file? ... even though I am only reading the first line!
the more number of lines I have, the more it is offsetting.
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