diff options
Diffstat (limited to 'doc/src/frameworks-technologies/containers.qdoc')
| -rw-r--r-- | doc/src/frameworks-technologies/containers.qdoc | 48 |
1 files changed, 24 insertions, 24 deletions
diff --git a/doc/src/frameworks-technologies/containers.qdoc b/doc/src/frameworks-technologies/containers.qdoc index 991588e..f28e5dc 100644 --- a/doc/src/frameworks-technologies/containers.qdoc +++ b/doc/src/frameworks-technologies/containers.qdoc @@ -205,7 +205,7 @@ Here's an example custom data type that meets the requirement of an assignable data type: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 0 + \snippet doc/src/snippets/code/doc_src_containers.cpp 0 If we don't provide a copy constructor or an assignment operator, C++ provides a default implementation that performs a @@ -306,7 +306,7 @@ Here's a typical loop for iterating through all the elements of a QList<QString> in order and printing them to the console: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 1 + \snippet doc/src/snippets/code/doc_src_containers.cpp 1 It works as follows: The QList to iterate over is passed to the QListIterator constructor. At that point, the iterator is located @@ -319,7 +319,7 @@ Here's how to iterate backward in a QList: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 2 + \snippet doc/src/snippets/code/doc_src_containers.cpp 2 The code is symmetric with iterating forward, except that we start by calling \l{QListIterator::toBack()}{toBack()} @@ -358,7 +358,7 @@ QMutableListIterator. Here's an example where we remove all odd numbers from a QList<int> using QMutableListIterator: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 3 + \snippet doc/src/snippets/code/doc_src_containers.cpp 3 The next() call in the loop is made every time. It jumps over the next item in the list. The @@ -368,13 +368,13 @@ the iterator, so it is safe to continue using it. This works just as well when iterating backward: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 4 + \snippet doc/src/snippets/code/doc_src_containers.cpp 4 If we just want to modify the value of an existing item, we can use \l{QMutableListIterator::setValue()}{setValue()}. In the code below, we replace any value larger than 128 with 128: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 5 + \snippet doc/src/snippets/code/doc_src_containers.cpp 5 Just like \l{QMutableListIterator::remove()}{remove()}, \l{QMutableListIterator::setValue()}{setValue()} operates on the @@ -387,7 +387,7 @@ operations, we don't even need \l{QMutableListIterator::setValue()}{setValue()}: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 6 + \snippet doc/src/snippets/code/doc_src_containers.cpp 6 As mentioned above, QLinkedList's, QVector's, and QSet's iterator classes have exactly the same API as QList's. We will now turn to @@ -410,7 +410,7 @@ The following example removes all (capital, country) pairs where the capital's name ends with "City": - \snippet doc/src/snippets/code/doc_src_containers.qdoc 7 + \snippet doc/src/snippets/code/doc_src_containers.cpp 7 QMapIterator also provides a key() and a value() function that operate directly on the iterator and that return the key and @@ -418,7 +418,7 @@ example, the following code copies the contents of a QMap into a QHash: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 8 + \snippet doc/src/snippets/code/doc_src_containers.cpp 8 If we want to iterate through all the items with the same value, we can use \l{QMapIterator::findNext()}{findNext()} @@ -426,7 +426,7 @@ Here's an example where we remove all the items with a particular value: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 9 + \snippet doc/src/snippets/code/doc_src_containers.cpp 9 \section2 STL-Style Iterators @@ -473,7 +473,7 @@ Here's a typical loop for iterating through all the elements of a QList<QString> in order and converting them to lowercase: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 10 + \snippet doc/src/snippets/code/doc_src_containers.cpp 10 Unlike \l{Java-style iterators}, STL-style iterators point directly at items. The begin() function of a container returns an @@ -493,7 +493,7 @@ decrement the iterator \e before we access the item. This requires a \c while loop: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 11 + \snippet doc/src/snippets/code/doc_src_containers.cpp 11 In the code snippets so far, we used the unary \c * operator to retrieve the item (of type QString) stored at a certain iterator @@ -504,7 +504,7 @@ For read-only access, you can use const_iterator, constBegin(), and constEnd(). For example: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 12 + \snippet doc/src/snippets/code/doc_src_containers.cpp 12 The following table summarizes the STL-style iterators' API: @@ -536,7 +536,7 @@ value() function to retrieve the value. For example, here's how we would print all items in a QMap to the console: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 13 + \snippet doc/src/snippets/code/doc_src_containers.cpp 13 Thanks to \l{implicit sharing}, it is very inexpensive for a function to return a container per value. The Qt API contains @@ -545,7 +545,7 @@ using an STL iterator, you should always take a copy of the container and iterate over the copy. For example: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 14 + \snippet doc/src/snippets/code/doc_src_containers.cpp 14 This problem doesn't occur with functions that return a const or non-const reference to a container. @@ -567,35 +567,35 @@ statement. For example, here's how to use \c foreach to iterate over a QLinkedList<QString>: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 15 + \snippet doc/src/snippets/code/doc_src_containers.cpp 15 The \c foreach code is significantly shorter than the equivalent code that uses iterators: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 16 + \snippet doc/src/snippets/code/doc_src_containers.cpp 16 Unless the data type contains a comma (e.g., \c{QPair<int, int>}), the variable used for iteration can be defined within the \c foreach statement: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 17 + \snippet doc/src/snippets/code/doc_src_containers.cpp 17 And like any other C++ loop construct, you can use braces around the body of a \c foreach loop, and you can use \c break to leave the loop: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 18 + \snippet doc/src/snippets/code/doc_src_containers.cpp 18 With QMap and QHash, \c foreach accesses the value component of the (key, value) pairs. If you want to iterate over both the keys and the values, you can use iterators (which are fastest), or you can write code like this: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 19 + \snippet doc/src/snippets/code/doc_src_containers.cpp 19 For a multi-valued map: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 20 + \snippet doc/src/snippets/code/doc_src_containers.cpp 20 Qt automatically takes a copy of the container when it enters a \c foreach loop. If you modify the container as you are @@ -611,12 +611,12 @@ In addition to \c foreach, Qt also provides a \c forever pseudo-keyword for infinite loops: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 21 + \snippet doc/src/snippets/code/doc_src_containers.cpp 21 If you're worried about namespace pollution, you can disable these macros by adding the following line to your \c .pro file: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 22 + \snippet doc/src/snippets/code/doc_src_containers.cpp 22 \section1 Other Container-Like Classes @@ -736,7 +736,7 @@ Consider the following code, which builds a QString from another QString: - \snippet doc/src/snippets/code/doc_src_containers.qdoc 23 + \snippet doc/src/snippets/code/doc_src_containers.cpp 23 We build the string \c out dynamically by appending one character to it at a time. Let's assume that we append 15000 characters to |