input and output questions about file

[Dic4000]

ÏÂÃæ³ÌÐò½¨Á¢²»Á ËÎļþ,²»ÖªµÀÄÄÀ ï³ö´íÁË?

Ö»Ï붨ÒåÒ»¸öfst reamÀàÐÍÀ´Íê³ÉÊ äÈëÊä³öµÄ¹¤×÷.
#include<iostre am>
#include<conio. h>
#include<fstrea m>

using namespace std;

int main()
{
fstream file("a.txt",fs tream::in|fstre am::out|fstream ::app);
string s1,s2;

if(!file) cerr<<"error"<< endl; //why the program have
//error when connecting
up "a.txt"

s1="abcd 1234\n";
file<<s1; //why don't write in a.txt?
file.flush();
file.seekg(0);
file>>s2;
cout<<"s2="<<s2 <<endl;//s2 is empty

file.close();

getch();
return 0;}

the program can run without any error,but the result is:

error

s2=

the program don't create file "a.txt",How do i do?

[Lew Pitcher]

On Feb 24, 10:13 am, "[e-mail] m" <[e-mail] mwrote:

ÏÂÃæ³ÌÐò½¨Á¢²»Á ËÎļþ,²»ÖªµÀÄÄÀ ï³ö´íÁË?

Ö»Ï붨ÒåÒ»¸öfst reamÀàÐÍÀ´Íê³ÉÊ äÈëÊä³öµÄ¹¤×÷.
#include<iostre am>
#include<conio. h>
#include<fstrea m>

using namespace std;

<snip>

the program can run without any error,but the result is:

error

s2=

the program don't create file "a.txt",How do i do?

You go talk to the guys in comp.lang.c++
Just down the hall, second door on the right (just after the koolade
dispenser)

--
Lew

[Simon Biber]

Di*****@163.com wrote:

ÏÂÃæ³ÌÐò½¨Á¢²»Á ËÎļþ,²»ÖªµÀÄÄÀ ï³ö´íÁË?

Ö»Ï붨ÒåÒ»¸öfst reamÀàÐÍÀ´Íê³ÉÊ äÈëÊä³öµÄ¹¤×÷.

ÏÂÃæ³ÌÐòÓÖ²»ÊÇC ÓïÑÔ£¬Äãµ½comp. lang.c++È¥°É¡£

The program below is not even in the C language. I suggest you go to
comp.lang.c++

--
Simon.

[Dic4000]

On 2ÔÂ24ÈÕ, ÏÂÎç11ʱ41·Ö, Simon Biber <[e-mail] wrote:

[e-mail] wrote:

ÏÂÃæ³ÌÐò½¨Á¢²»Á ËÎļþ,²»ÖªµÀÄÄÀ ï³ö´íÁË?

Ö»Ï붨ÒåÒ»¸öfst reamÀàÐÍÀ´Íê³ÉÊ äÈëÊä³öµÄ¹¤×÷.

ÏÂÃæ³ÌÐòÓÖ²»ÊÇC ÓïÑÔ£¬Äãµ½comp. lang.c++È¥°É¡£

The program below is not even in the C language. I suggest you go to
comp.lang.c++

--
Simon.

I see.

[Martin Ambuhl]

Di*****@163.com wrote:

下é�¢ç¨‹åº�建 ç«‹ä¸�了文件 ,ä¸�知é�“å“ªé‡ Œå‡ºé”™äº†?

å�ªæƒ³å®šä¹‰ä¸€ 个fstreamç±»åž ‹æ�¥å®Œæˆ�è¾“å… ¥è¾“å‡ºçš„å·¥ä½ œ.
#include<iostre am>
#include<conio. h>
#include<fstrea m>

<iostreamand <fstreamare C++ headers. They are not part of C;
questions involving anything associated with those headers belong in
<news:comp.lang .c++>, not <news:comp.lang .c>.

<conio.his not a standard C or C++ header. Any questions involving
anthing associated with that header should go to an
implementation-specific newgroup, mailing-list, or technical support.
They do not belong here (comp.lang.c) or in comp.lang.c++.

>
using namespace std;

That is a syntax error in C.

[Mark McIntyre]

On 24 Feb 2007 07:13:08 -0800, in comp.lang.c , "Di*****@163.co m"
<Di*****@163.co mwrote:

>using namespace std;

comp.lang.c++ is down the hall, second left.
--
Mark McIntyre

"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it."
--Brian Kernighan

[CBFalconer]

"Di*****@163.co m" wrote:

>

.... snip incomprehensibl e ...

>
#include<iostre am>
#include<conio. h>
#include<fstrea m>

using namespace std;

int main()
{
fstream file("a.txt",fs tream::in|fstre am::out|fstream ::app);
string s1,s2;

if(!file) cerr<<"error"<< endl; //why the program have
//error when connecting
up "a.txt"

s1="abcd 1234\n";
file<<s1; //why don't write in a.txt?
file.flush();
file.seekg(0);
file>>s2;
cout<<"s2="<<s2 <<endl;//s2 is empty

file.close();

getch();
return 0;}

the program can run without any error,but the result is:

Don't believe you.

junk.c:1:19: iostream: No such file or directory (ENOENT)
junk.c:2:18: conio.h: No such file or directory (ENOENT)
junk.c:3:18: fstream: No such file or directory (ENOENT)
junk.c:5: parse error before "namespace"
junk.c:5: warning: type defaults to `int' in declaration of `std'
junk.c:5: ISO C forbids data definition with no type or storage
class
junk.c: In function `main':
junk.c:9: `fstream' undeclared (first use in this function)
junk.c:9: (Each undeclared identifier is reported only once
junk.c:9: for each function it appears in.)
junk.c:9: parse error before "file"
junk.c:10: `string' undeclared (first use in this function)
junk.c:12: `file' undeclared (first use in this function)
junk.c:12: `cerr' undeclared (first use in this function)
junk.c:12: `endl' undeclared (first use in this function)
junk.c:12: parse error before '/' token
junk.c:17: `s1' undeclared (first use in this function)
junk.c:17: parse error before '/' token
junk.c:17:24: missing terminating ' character
junk.c:17:24: warning: character constant too long
junk.c:20: `s2' undeclared (first use in this function)
junk.c:21: `cout' undeclared (first use in this function)
junk.c:21: parse error before '/' token
junk.c:25: warning: implicit declaration of function `getch'

c != C++

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>