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path: root/doc/src/examples/factorial.qdoc
 ```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 ``` ``````/**************************************************************************** ** ** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). ** Contact: http://www.qt-project.org/ ** ** This file is part of the documentation of the Qt Toolkit. ** ** \$QT_BEGIN_LICENSE:FDL\$ ** GNU Free Documentation License ** Alternatively, this file may be used under the terms of the GNU Free ** Documentation License version 1.3 as published by the Free Software ** Foundation and appearing in the file included in the packaging of ** this file. ** ** Other Usage ** Alternatively, this file may be used in accordance with the terms ** and conditions contained in a signed written agreement between you ** and Nokia. ** ** ** ** ** ** \$QT_END_LICENSE\$ ** ****************************************************************************/ /*! \example statemachine/factorial \title Factorial States Example The Factorial States example shows how to use \l{The State Machine Framework} to calculate the factorial of an integer. The statechart for calculating the factorial looks as follows: \image factorial-example.png \omit \caption This is a caption \endomit In other words, the state machine calculates the factorial of 6 and prints the result. \snippet examples/statemachine/factorial/main.cpp 0 The Factorial class is used to hold the data of the computation, \c x and \c fac. It also provides a signal that's emitted whenever the value of \c x changes. \snippet examples/statemachine/factorial/main.cpp 1 The FactorialLoopTransition class implements the guard (\c x > 1) and calculations (\c fac = \c x * \c fac; \c x = \c x - 1) of the factorial loop. \snippet examples/statemachine/factorial/main.cpp 2 The FactorialDoneTransition class implements the guard (\c x <= 1) that terminates the factorial computation. It also prints the final result to standard output. \snippet examples/statemachine/factorial/main.cpp 3 The application's main() function first creates the application object, a Factorial object and a state machine. \snippet examples/statemachine/factorial/main.cpp 4 The \c compute state is created, and the initial values of \c x and \c fac are defined. A FactorialLoopTransition object is created and added to the state. \snippet examples/statemachine/factorial/main.cpp 5 A final state, \c done, is created, and a FactorialDoneTransition object is created with \c done as its target state. The transition is then added to the \c compute state. \snippet examples/statemachine/factorial/main.cpp 6 The machine's initial state is set to be the \c compute state. We connect the QStateMachine::finished() signal to the QCoreApplication::quit() slot, so the application will quit when the state machine's work is done. Finally, the state machine is started, and the application's event loop is entered. */ ``````