C++ Filehandling: Difference between ios:app and ios:ate?
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What's the difference between ios::ate and ios:app when writing to a file.
In my view, ios::app gives you the ability to move around in the file, whereas with ios::ate it can only read/write at the end of the file. Is this correct?
c++ file fstream c++-standard-library
edited Jul 19 '16 at 12:57
iammilind
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asked Apr 28 '12 at 1:12
Adam_G
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up vote
51
down vote
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What's the difference between ios::ate and ios:app when writing to a file.
In my view, ios::app gives you the ability to move around in the file, whereas with ios::ate it can only read/write at the end of the file. Is this correct?
c++ file fstream c++-standard-library
edited Jul 19 '16 at 12:57
iammilind
43.8k19122246
asked Apr 28 '12 at 1:12
Adam_G
2,170114592
add a comment |
up vote
51
down vote
favorite
up vote
51
down vote
favorite
What's the difference between ios::ate and ios:app when writing to a file.
In my view, ios::app gives you the ability to move around in the file, whereas with ios::ate it can only read/write at the end of the file. Is this correct?
c++ file fstream c++-standard-library
edited Jul 19 '16 at 12:57
iammilind
43.8k19122246
asked Apr 28 '12 at 1:12
Adam_G
2,170114592
What's the difference between ios::ate and ios:app when writing to a file.
In my view, ios::app gives you the ability to move around in the file, whereas with ios::ate it can only read/write at the end of the file. Is this correct?
c++ file fstream c++-standard-library
c++ file fstream c++-standard-library
edited Jul 19 '16 at 12:57
iammilind
43.8k19122246
asked Apr 28 '12 at 1:12
Adam_G
2,170114592
edited Jul 19 '16 at 12:57
iammilind
43.8k19122246
asked Apr 28 '12 at 1:12
Adam_G
2,170114592
edited Jul 19 '16 at 12:57
iammilind
43.8k19122246
edited Jul 19 '16 at 12:57
iammilind
43.8k19122246
edited Jul 19 '16 at 12:57
iammilind
43.8k19122246
43.8k19122246
asked Apr 28 '12 at 1:12
Adam_G
2,170114592
asked Apr 28 '12 at 1:12
Adam_G
2,170114592
asked Apr 28 '12 at 1:12
Adam_G
2,170114592
2,170114592
add a comment |
add a comment |
5 Answers
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61
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It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write elsewhere.
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
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30
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They are specified as follows (in 27.5.3.1.4 of C++11):
appseek to end before each write
ateopen and seek to end immediately after opening
With ios::app the write position in the file is "sticky" -- all writes are at the end, no matter where you seek.
answered Apr 28 '12 at 1:16
Steve Jessop
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up vote
19
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It is pretty good documented here.
ios::ate "sets the stream's position indicator to the end of the stream on opening."
ios:app "set the stream's position indicator to the end of the stream before each output operation."
This means the difference that ios::ate puts your position to the end of the file when you open it. ios::app instead puts it at the end of the file every time you flush your stream. If for example you two programs that write to the same log file ios:ate will override anything that was added to the file by the other program since your program opened it. ios:app will instead jump to the end of file each time your programm adds a log entry.
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
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up vote
7
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App:
we cannot move the pointer.It will be only at end
Ate:
we can move the record pointer to any other place
answered Sep 23 '13 at 10:14
naveen
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up vote
0
down vote
The ios::ate option is for input and output operations and
ios::app allows us to add data to the end of file.
edited May 17 at 6:08
Jonathan Rys
1,136520
answered May 17 at 2:03
toijam sonalika devi
1
Can you provide a link to documentation?
– harvpan
May 17 at 2:27
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protected by Hovercraft Full Of Eels Nov 11 at 22:07
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5 Answers
5
active
oldest
votes
5 Answers
5
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
61
down vote
accepted
It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write elsewhere.
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
add a comment |
up vote
61
down vote
accepted
It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write elsewhere.
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
add a comment |
up vote
61
down vote
accepted
up vote
61
down vote
accepted
It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write elsewhere.
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write elsewhere.
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
answered Apr 28 '12 at 1:17
Jon Purdy
37.6k666125
37.6k666125
add a comment |
add a comment |
up vote
30
down vote
They are specified as follows (in 27.5.3.1.4 of C++11):
appseek to end before each write
ateopen and seek to end immediately after opening
With ios::app the write position in the file is "sticky" -- all writes are at the end, no matter where you seek.
answered Apr 28 '12 at 1:16
Steve Jessop
231k25365622
add a comment |
up vote
30
down vote
They are specified as follows (in 27.5.3.1.4 of C++11):
appseek to end before each write
ateopen and seek to end immediately after opening
With ios::app the write position in the file is "sticky" -- all writes are at the end, no matter where you seek.
answered Apr 28 '12 at 1:16
Steve Jessop
231k25365622
add a comment |
up vote
30
down vote
up vote
30
down vote
They are specified as follows (in 27.5.3.1.4 of C++11):
appseek to end before each write
ateopen and seek to end immediately after opening
With ios::app the write position in the file is "sticky" -- all writes are at the end, no matter where you seek.
answered Apr 28 '12 at 1:16
Steve Jessop
231k25365622
They are specified as follows (in 27.5.3.1.4 of C++11):
appseek to end before each write
ateopen and seek to end immediately after opening
With ios::app the write position in the file is "sticky" -- all writes are at the end, no matter where you seek.
answered Apr 28 '12 at 1:16
Steve Jessop
231k25365622
answered Apr 28 '12 at 1:16
Steve Jessop
231k25365622
answered Apr 28 '12 at 1:16
Steve Jessop
231k25365622
answered Apr 28 '12 at 1:16
Steve Jessop
231k25365622
231k25365622
add a comment |
add a comment |
up vote
19
down vote
It is pretty good documented here.
ios::ate "sets the stream's position indicator to the end of the stream on opening."
ios:app "set the stream's position indicator to the end of the stream before each output operation."
This means the difference that ios::ate puts your position to the end of the file when you open it. ios::app instead puts it at the end of the file every time you flush your stream. If for example you two programs that write to the same log file ios:ate will override anything that was added to the file by the other program since your program opened it. ios:app will instead jump to the end of file each time your programm adds a log entry.
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
add a comment |
up vote
19
down vote
It is pretty good documented here.
ios::ate "sets the stream's position indicator to the end of the stream on opening."
ios:app "set the stream's position indicator to the end of the stream before each output operation."
This means the difference that ios::ate puts your position to the end of the file when you open it. ios::app instead puts it at the end of the file every time you flush your stream. If for example you two programs that write to the same log file ios:ate will override anything that was added to the file by the other program since your program opened it. ios:app will instead jump to the end of file each time your programm adds a log entry.
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
add a comment |
up vote
19
down vote
up vote
19
down vote
It is pretty good documented here.
ios::ate "sets the stream's position indicator to the end of the stream on opening."
ios:app "set the stream's position indicator to the end of the stream before each output operation."
This means the difference that ios::ate puts your position to the end of the file when you open it. ios::app instead puts it at the end of the file every time you flush your stream. If for example you two programs that write to the same log file ios:ate will override anything that was added to the file by the other program since your program opened it. ios:app will instead jump to the end of file each time your programm adds a log entry.
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
It is pretty good documented here.
ios::ate "sets the stream's position indicator to the end of the stream on opening."
ios:app "set the stream's position indicator to the end of the stream before each output operation."
This means the difference that ios::ate puts your position to the end of the file when you open it. ios::app instead puts it at the end of the file every time you flush your stream. If for example you two programs that write to the same log file ios:ate will override anything that was added to the file by the other program since your program opened it. ios:app will instead jump to the end of file each time your programm adds a log entry.
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
edited Mar 13 '16 at 13:41
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
answered Apr 28 '12 at 1:21
Haatschii
4,59883982
4,59883982
add a comment |
add a comment |
up vote
7
down vote
App:
we cannot move the pointer.It will be only at end
Ate:
we can move the record pointer to any other place
answered Sep 23 '13 at 10:14
naveen
8711
add a comment |
up vote
7
down vote
App:
we cannot move the pointer.It will be only at end
Ate:
we can move the record pointer to any other place
answered Sep 23 '13 at 10:14
naveen
8711
add a comment |
up vote
7
down vote
up vote
7
down vote
App:
we cannot move the pointer.It will be only at end
Ate:
we can move the record pointer to any other place
answered Sep 23 '13 at 10:14
naveen
8711
App:
we cannot move the pointer.It will be only at end
Ate:
we can move the record pointer to any other place
answered Sep 23 '13 at 10:14
naveen
8711
answered Sep 23 '13 at 10:14
naveen
8711
answered Sep 23 '13 at 10:14
naveen
8711
answered Sep 23 '13 at 10:14
naveen
8711
8711
add a comment |
add a comment |
up vote
0
down vote
The ios::ate option is for input and output operations and
ios::app allows us to add data to the end of file.
edited May 17 at 6:08
Jonathan Rys
1,136520
answered May 17 at 2:03
toijam sonalika devi
1
Can you provide a link to documentation?
– harvpan
May 17 at 2:27
add a comment |
up vote
0
down vote
The ios::ate option is for input and output operations and
ios::app allows us to add data to the end of file.
edited May 17 at 6:08
Jonathan Rys
1,136520
answered May 17 at 2:03
toijam sonalika devi
1
Can you provide a link to documentation?
– harvpan
May 17 at 2:27
add a comment |
up vote
0
down vote
up vote
0
down vote
The ios::ate option is for input and output operations and
ios::app allows us to add data to the end of file.
edited May 17 at 6:08
Jonathan Rys
1,136520
answered May 17 at 2:03
toijam sonalika devi
1
The ios::ate option is for input and output operations and
ios::app allows us to add data to the end of file.
edited May 17 at 6:08
Jonathan Rys
1,136520
answered May 17 at 2:03
toijam sonalika devi
1
edited May 17 at 6:08
Jonathan Rys
1,136520
edited May 17 at 6:08
Jonathan Rys
1,136520
edited May 17 at 6:08
Jonathan Rys
1,136520
1,136520
answered May 17 at 2:03
toijam sonalika devi
1
answered May 17 at 2:03
toijam sonalika devi
1
answered May 17 at 2:03
toijam sonalika devi
1
1
Can you provide a link to documentation?
– harvpan
May 17 at 2:27
add a comment |
Can you provide a link to documentation?
– harvpan
May 17 at 2:27
Can you provide a link to documentation?
– harvpan
May 17 at 2:27
Can you provide a link to documentation?
– harvpan
May 17 at 2:27
add a comment |
protected by Hovercraft Full Of Eels Nov 11 at 22:07
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?
