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Dec 18, 2010 Wow dude, sorry I didn't see this post earilier, linker errors can be tough. In wxDev-C (which I remeber is simular enough to Dev-C) you have to include the.h in your project by clicking Project - Add to Project then navigate to the.h you made, this tells the makefile to include the header file in your project. Create a file if one doesn't exist - C. Ask Question. There's no way to open read-only on the condition that it exists without creating a needless race condition.
-->This step-by-step walkthrough shows how to create a static library (.lib file) for use with C++ apps. Using a static library is a great way to reuse code. Rather than reimplementing the same routines in every app that requires the functionality, you write them one time in a static library and then reference it from the apps. Code linked from a static library becomes part of your app—you don't have to install another file to use the code.
This walkthrough covers these tasks:
Prerequisites
An understanding of the fundamentals of the C++ language.
Create a static library project
The instructions for how to create the project vary depending on your version of Visual Studio. To see the documentation for your preferred version of Visual Studio, use the Version selector control. It's found at the top of the table of contents on this page.
To create a static library project in Visual Studio 2019
- On the menu bar, choose File > New > Project to open the Create a New Project dialog box.
- At the top of the dialog, set Language to C++, set Platform to Windows, and set Project type to Library.
- From the filtered list of project types, select Windows Desktop Wizard, then choose Next.
- In the Configure your new project page, enter MathLibrary in the Project name box to specify a name for the project. Enter StaticMath in the Solution name box. Choose the Create button to open the Windows Desktop Project dialog.
- In the Windows Desktop Project dialog, under Application type, select Static Library (.lib).
- Under Additional options, uncheck the Precompiled header check box if it's checked. Check the Empty project box.
- Choose OK to create the project.
To create a static library project in Visual Studio 2017
- On the menu bar, choose File > New > Project.
- In the New Project dialog box, select Installed > Visual C++ > Windows Desktop. In the center pane, select Windows Desktop Wizard.
- Specify a name for the project—for example, MathLibrary—in the Name box. Specify a name for the solution—for example, StaticMath—in the Solution Name box. Choose the OK button.
- In the Windows Desktop Project dialog, under Application type, select Static Library (.lib).
- Under Additional Options, uncheck the Precompiled header check box if it's checked. Check the Empty project box. How to download documents from iphone to mac.
- Choose OK to create the project.
To create a static library project in Visual Studio 2015
- On the menu bar, choose File > New > Project.
- In the New Project dialog box, select Installed > Templates > Visual C++ > Win32. In the center pane, select Win32 Console Application.
- Specify a name for the project—for example, MathLibrary—in the Name box. Specify a name for the solution—for example, StaticMath—in the Solution Name box. Choose the OK button.
- In the Win32 Application Wizard, choose Next.
- In the Application Settings page, under Application type, select Static library. Under Additional options, uncheck the Precompiled header checkbox. Choose Finish to create the project.
Add a class to the static library
To add a class to the static library
- To create a header file for a new class, right-click to open the shortcut menu for the MathLibrary project in Solution Explorer, and then choose Add > New Item.
- In the Add New Item dialog box, select Visual C++ > Code. In the center pane, select Header File (.h). Specify a name for the header file—for example, MathLibrary.h—and then choose the Add button. A nearly blank header file is displayed.
- Add a declaration for a class named
Arithmetic
to do common mathematical operations such as addition, subtraction, multiplication, and division. The code should resemble: - To create a source file for the new class, open the shortcut menu for the MathLibrary project in Solution Explorer, and then choose Add > New Item.
- In the Add New Item dialog box, in the center pane, select C++ File (.cpp). Specify a name for the source file—for example, MathLibrary.cpp—and then choose the Add button. A blank source file is displayed.
- https://greatandmore.weebly.com/c-devt-type.html. Use this source file to implement the functionality for class
Arithmetic
. The code should resemble: - To build the static library, select Build > Build Solution on the menu bar. The build creates a static library, MathLibrary.lib, that can be used by other programs.NoteWhen you build on the Visual Studio command line, you must build the program in two steps. First, run
cl /c /EHsc MathLibrary.cpp
to compile the code and create an object file that's named MathLibrary.obj. (Thecl
command invokes the compiler, Cl.exe, and the/c
option specifies compile without linking. For more information, see /c (Compile Without Linking).) Second, runlib MathLibrary.obj
to link the code and create the static library MathLibrary.lib. (Thelib
command invokes the Library Manager, Lib.exe. For more information, see LIB Reference.)
Create a C++ console app that references the static library
To create a C++ console app that references the static library in Visual Studio 2019
- In Solution Explorer, right-click on the top node, Solution 'StaticMath', to open the shortcut menu. Choose Add > New Project to open the Add a New Project dialog box.
- At the top of the dialog, set the Project type filter to Console.
- From the filtered list of project types, choose Console App then choose Next. In the next page, enter MathClient in the Name box to specify a name for the project.
- Choose the Create Redcine x pro download mac. button to create the client project.
- After you create a console app, an empty program is created for you. The name for the source file is the same as the name that you chose earlier. In the example, it's named
MathClient.cpp
.
To create a C++ console app that references the static library in Visual Studio 2017
- In Solution Explorer, right-click on the top node, Solution 'StaticMath', to open the shortcut menu. Choose Add > New Project to open the Add a New Project dialog box.
- In the Add New Project dialog box, select Installed > Visual C++ > Windows Desktop. In the center pane, select Windows Desktop Wizard.
- Specify a name for the project—for example, MathClient—in the Name box. Choose the OK button.
- Dev c++ version 5.11. In the Windows Desktop Project dialog, under Application type, select Console Application (.exe).
- Under Additional Options, uncheck the Precompiled header check box if it's checked.
- Choose OK to create the project.
- After you create a console app, an empty program is created for you. The name for the source file is the same as the name that you chose earlier. In the example, it's named
MathClient.cpp
.
To create a C++ console app that references the static library in Visual Studio 2015
- In Solution Explorer, right-click on the top node, Solution 'StaticMath', to open the shortcut menu. Choose Add > New Project to open the Add a New Project dialog box.
- In the Add New Project dialog box, select Installed > Visual C++ > Win32. In the center pane, select Win32 Console Application. Mac cannot force quit app.
- Specify a name for the project—for example, MathClient—in the Name box. Choose the OK button.
- In the Win32 Application Wizard dialog, choose Next.
- On the Application Settings page, under Application type, make sure Console application is selected. Under Additional options, uncheck Precompiled header, then check the Empty Project checkbox. Choose Finish to create the project.
- To add a source file to the empty project, right-click to open the shortcut menu for the MathClient project in Solution Explorer, and then choose Add > New Item.
- In the Add New Item dialog box, select Visual C++ > Code. In the center pane, select C++ File (.cpp). Specify a name for the source file—for example, MathClient.cpp—and then choose the Add button. A blank source file is displayed.
Use the functionality from the static library in the app
To use the functionality from the static library in the app
- Before you can use the math routines in the static library, you must reference it. Open the shortcut menu for the MathClient project in Solution Explorer, and then choose Add > Reference.
- The Add Reference dialog box lists the libraries that you can reference. The Projects tab lists the projects in the current solution and any libraries they reference. Open the Projects tab, select the MathLibrary check box, and then choose the OK button.
- To reference the
MathLibrary.h
header file, you must modify the included directories path. In Solution Explorer, right-click on MathClient to open the shortcut menu. Choose Properties to open the MathClient Property Pages dialog box. - In the MathClient Property Pages dialog box, set the Configuration drop-down to All Configurations. Set the Platform drop-down to All Platforms.
- Select the Configuration Properties > C/C++ > General property page. In the Additional Include Directories property, specify the path of the MathLibrary directory, or browse for it.To browse for the directory path:
- Sam cooke download change gonna come. Open the Additional Include Directories property value drop-down list, and then choose Edit.
- In the Additional Include Directories dialog box, double-click in the top of the text box. Then choose the ellipsis button (.) at the end of the line.
- In the Select Directory dialog box, navigate up a level, and then select the MathLibrary directory. Then choose the Select Folder button to save your selection.
- In the Additional Include Directories dialog box, choose the OK button.
- In the Property Pages dialog box, choose the OK button to save your changes to the project. Download traktor pro 2 full free.
- You can now use the
Arithmetic
class in this app by including the#include 'MathLibrary.h'
header in your code. Replace the contents ofMathClient.cpp
with this code: - To build the executable, choose Build > Build Solution on the menu bar. Key generator sony vegas pro 12.
Run the app
To run the app
- Make sure that MathClient is selected as the default project. To select it, right-click to open the shortcut menu for MathClient in Solution Explorer, and then choose Set as StartUp Project.
- To run the project, on the menu bar, choose Debug > Start Without Debugging. The output should resemble:
See also
Walkthrough: Creating and Using a Dynamic Link Library (C++)
Desktop Applications (Visual C++)
https://juiceclever266.weebly.com/download-rhino-trial-for-mac.html.
C++ provides the following classes to perform output and input of characters to/from files: Desktop Applications (Visual C++)
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ofstream
: Stream class to write on filesifstream
: Stream class to read from filesfstream
: Stream class to both read and write from/to files.
These classes are derived directly or indirectly from the classes
istream
and ostream
. We have already used objects whose types were these classes: cin
is an object of class istream
and cout
is an object of class ostream
. Therefore, we have already been using classes that are related to our file streams. And in fact, we can use our file streams the same way we are already used to use cin
and cout
, with the only difference that we have to associate these streams with physical files. Let's see an example:This code creates a file called
example.txt
and inserts a sentence into it in the same way we are used to do with cout
, but using the file stream myfile
instead.But let's go step by step:
Open a file
The first operation generally performed on an object of one of these classes is to associate it to a real file. This procedure is known as to open a file. An open file is represented within a program by a stream (i.e., an object of one of these classes; in the previous example, this wasmyfile
) and any input or output operation performed on this stream object will be applied to the physical file associated to it.In order to open a file with a stream object we use its member function
open
:open (filename, mode);
Where
filename
is a string representing the name of the file to be opened, and mode
is an optional parameter with a combination of the following flags:ios::in | Open for input operations. |
ios::out | Open for output operations. |
ios::binary | Open in binary mode. |
ios::ate | Set the initial position at the end of the file. If this flag is not set, the initial position is the beginning of the file. |
ios::app | All output operations are performed at the end of the file, appending the content to the current content of the file. |
ios::trunc | If the file is opened for output operations and it already existed, its previous content is deleted and replaced by the new one. |
All these flags can be combined using the bitwise operator OR (
|
). For example, if we want to open the file example.bin
in binary mode to add data we could do it by the following call to member function open
:Each of the
open
member functions of classes ofstream
, ifstream
and fstream
has a default mode that is used if the file is opened without a second argument:class | default mode parameter |
---|---|
ofstream | ios::out |
ifstream | ios::in |
fstream | ios::in | ios::out |
For
ifstream
and ofstream
classes, ios::in
and ios::out
are automatically and respectively assumed, even if a mode that does not include them is passed as second argument to the open
member function (the flags are combined).For
fstream
, the default value is only applied if the function is called without specifying any value for the mode parameter. If the function is called with any value in that parameter the default mode is overridden, not combined.File streams opened in binary mode perform input and output operations independently of any format considerations. Non-binary files are known as text files, and some translations may occur due to formatting of some special characters (like newline and carriage return characters).
Since the first task that is performed on a file stream is generally to open a file, these three classes include a constructor that automatically calls the
open
![Download Download](/uploads/1/2/6/0/126047866/658994783.png)
myfile
object and conduct the same opening operation in our previous example by writing:Combining object construction and stream opening in a single statement. Both forms to open a file are valid and equivalent.
To check if a file stream was successful opening a file, you can do it by calling to member
is_open
. This member function returns a bool
value of true
in the case that indeed the stream object is associated with an open file, or false
otherwise:Closing a file
When we are finished with our input and output operations on a file we shall close it so that the operating system is notified and its resources become available again. For that, we call the stream's member functionclose
. This member function takes flushes the associated buffers and closes the file:Once this member function is called, the stream object can be re-used to open another file, and the file is available again to be opened by other processes.
In case that an object is destroyed while still associated with an open file, the destructor automatically calls the member function
close
.Text files
Text file streams are those where theios::binary
flag is not included in their opening mode. These files are designed to store text and thus all values that are input or output from/to them can suffer some formatting transformations, which do not necessarily correspond to their literal binary value.Writing operations on text files are performed in the same way we operated with
cout
:Reading from a file can also be performed in the same way that we did with
cin
:This last example reads a text file and prints out its content on the screen. We have created a while loop that reads the file line by line, using getline. The value returned by getline is a reference to the stream object itself, which when evaluated as a boolean expression (as in this while-loop) is
true
if the stream is ready for more operations, and false
if either the end of the file has been reached or if some other error occurred.Checking state flags
The following member functions exist to check for specific states of a stream (all of them return abool
value): bad()
- Returns
true
if a reading or writing operation fails. For example, in the case that we try to write to a file that is not open for writing or if the device where we try to write has no space left. fail()
- Returns
true
in the same cases asbad()
, but also in the case that a format error happens, like when an alphabetical character is extracted when we are trying to read an integer number. eof()
- Returns
true
if a file open for reading has reached the end. good()
- It is the most generic state flag: it returns
false
in the same cases in which calling any of the previous functions would returntrue
. Note thatgood
andbad
are not exact opposites (good
checks more state flags at once).
The member function
clear()
can be used to reset the state flags.get and put stream positioning
All i/o streams objects keep internally -at least- one internal position:ifstream
, like istream
, keeps an internal get position with the location of the element to be read in the next input operation.ofstream
, like ostream
, keeps an internal put position with the location where the next element has to be written.Finally,
fstream
, keeps both, the get and the put position, like iostream
.These internal stream positions point to the locations within the stream where the next reading or writing operation is performed. These positions can be observed and modified using the following member functions:
tellg() and tellp()
These two member functions with no parameters return a value of the member type![Use Use](/uploads/1/2/6/0/126047866/157926278.png)
streampos
, which is a type representing the current get position (in the case of tellg
) or the put position (in the case of tellp
).seekg() and seekp()
These functions allow to change the location of the get and put positions. Both functions are overloaded with two different prototypes. The first form is:seekg ( position );
seekp ( position );
Using this prototype, the stream pointer is changed to the absolute position
position
(counting from the beginning of the file). The type for this parameter is streampos
, which is the same type as returned by functions tellg
and tellp
.The other form for these functions is:
seekg ( offset, direction );
seekp ( offset, direction );
Using this prototype, the get or put position is set to an offset value relative to some specific point determined by the parameter
direction
. offset
is of type streamoff
. And direction
is of type seekdir
, which is an enumerated type that determines the point from where offset is counted from, and that can take any of the following values:ios::beg | offset counted from the beginning of the stream |
ios::cur | offset counted from the current position |
ios::end | offset counted from the end of the stream |
The following example uses the member functions we have just seen to obtain the size of a file:
Notice the type we have used for variables
begin
and end
:streampos
is a specific type used for buffer and file positioning and is the type returned by file.tellg()
. Values of this type can safely be subtracted from other values of the same type, and can also be converted to an integer type large enough to contain the size of the file.These stream positioning functions use two particular types:
streampos
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andstreamoff
. These types are also defined as member types of the stream class:Type | Member type | Description |
---|---|---|
streampos | ios::pos_type | Defined as fpos<mbstate_t> .It can be converted to/from streamoff and can be added or subtracted values of these types. |
streamoff | ios::off_type | It is an alias of one of the fundamental integral types (such as int or long long ). |
Each of the member types above is an alias of its non-member equivalent (they are the exact same type). It does not matter which one is used. The member types are more generic, because they are the same on all stream objects (even on streams using exotic types of characters), but the non-member types are widely used in existing code for historical reasons.
Binary files
For binary files, reading and writing data with the extraction and insertion operators (<<
and >>
) and functions like getline
is not efficient, since we do not need to format any data and data is likely not formatted in lines.File streams include two member functions specifically designed to read and write binary data sequentially:
write
and read
. The first one (write
) is a member function of ostream
(inherited by ofstream
). And read
is a member function of istream
(inherited by ifstream
). Objects of class fstream
have both. Their prototypes are:write ( memory_block, size );
read ( memory_block, size );
Where
memory_block
is of type char*
(pointer to char
), and represents the address of an array of bytes where the read data elements are stored or from where the data elements to be written are taken. The size
parameter is an integer value that specifies the number of characters to be read or written from/to the memory block.In this example, the entire file is read and stored in a memory block. Let's examine how this is done:
First, the file is open with the
ios::ate
flag, which means that the get pointer will be positioned at the end of the file. This way, when we call to member tellg()
, we will directly obtain the size of the file.Once we have obtained the size of the file, we request the allocation of a memory block large enough to hold the entire file:
Right after that, we proceed to set the get position at the beginning of the file (remember that we opened the file with this pointer at the end), then we read the entire file, and finally close it:
At this point we could operate with the data obtained from the file. But our program simply announces that the content of the file is in memory and then finishes.
Buffers and Synchronization
When we operate with file streams, these are associated to an internal buffer object of typestreambuf
. This buffer object may represent a memory block that acts as an intermediary between the stream and the physical file. For example, with an ofstream
, each time the member function put
(which writes a single character) is called, the character may be inserted in this intermediate buffer instead of being written directly to the physical file with which the stream is associated.The operating system may also define other layers of buffering for reading and writing to files.
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When the buffer is flushed, all the data contained in it is written to the physical medium (if it is an output stream). This process is called synchronization and takes place under any of the following circumstances:Dev C++ Creating A C++ Files
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- When the file is closed: before closing a file, all buffers that have not yet been flushed are synchronized and all pending data is written or read to the physical medium.
- When the buffer is full: Buffers have a certain size. When the buffer is full it is automatically synchronized.
- Explicitly, with manipulators: When certain manipulators are used on streams, an explicit synchronization takes place. These manipulators are:
flush
andendl
. - Explicitly, with member function sync(): Calling the stream's member function
sync()
causes an immediate synchronization. This function returns anint
value equal to -1 if the stream has no associated buffer or in case of failure. Otherwise (if the stream buffer was successfully synchronized) it returns0
.
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