1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
// -*- mode: c++; mode: visual-line; mode: flyspell; fill-column: 100000 -*-
/***************************************************************************
* doc/tutorial_vector.dox
*
* Usage Tutorial for STXXL
*
* Part of the STXXL. See http://stxxl.sourceforge.net
*
* Copyright (C) 2013 Timo Bingmann <tb@panthema.net>
* Copyright (C) 2013 Daniel Feist <daniel.feist@student.kit.edu>
*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
**************************************************************************/
namespace stxxl {
/** \page tutorial_vector STXXL Vector
This section introduces into the STXXL vector container (to learn more about the structure of stxxl::vector, see section \ref design_vector).
### Creating a STXXL vector
Before we can use a STXXL vector, we first have to define and then to instantiate a vector object.
To manage the configuration of the vector type we use the generator template. A minimal configuration is shown below - as one can see the value_type (integer in our case) is the only only stricly neccessary
parameter. See \ref design_vector_generator for additional configuration parameters and information.
\code
typedef stxxl::VECTOR_GENERATOR<int>::result vector;
vector my_vector; // creates empty vector object
\endcode
### Insert elements
We can fill the vector by calling push_back() which appends a new value at the end:
\code
for (int i = 0; i < 1024*1024; i++)
{
my_vector.push_back(i);
}
// my_vector stores: 0 1 2 3 4 5 6 [...] 1024*1024
\endcode
### Access elements
To read and/or modify the values of a STXXL vector, simply use the []-operator:
\code
std::cout << "element at position 99: " << my_vector[99] << std::endl;
my_vector[99] = 0; // zeroing element at position 99
\endcode
In addition, the STXXL vector provides different iterators to advance the vector which can be used as follows:
\code
// create iterator which starts at the beginning of my_vector
vector::iterator iter = my_vector.begin();
// access an element
std::cout << "first element: " << *iter << std::endl;
// go to next element
iter++;
\endcode
Alongside with the many advantages of iterators, there are several things which need to bear in mind when using them. Details are described in \ref design_vector_notes.
### Delete elements
The operation pop_back() removes the last element of the vector (without returning it). The following code snippet is emptying my_vector:
\code
// empty() returns true, if the vector is empty
while (!my_vector.empty()) {
my_vector.pop_back();
}
\endcode
### Determine size / Check whether vector is empty
To determine the number of elements a vector currently stores, call size():
\code
std::cout << "size of vector: " << my_vector.size() << std::endl;
\endcode
To check if the vector is empty, call the empty() function which returns true in that case:
\code
std::cout << "vector empty? " << my_vector.empty() << std::endl;
\endcode
### A minimal working example of STXXL's vector
(See \ref examples/containers/vector1.cpp for the sourcecode of the following example).
\snippet examples/containers/vector1.cpp example
See \ref examples/containers/vector2.cpp for the sourcecode of a more comprehensive example.
\example examples/containers/vector1.cpp
This example code is explained in the \ref tutorial_vector section.
\example examples/containers/vector2.cpp
This example code is explained in the \ref tutorial_vector section.
*/
} // namespace stxxl
|
