Method 10 in C that declares the class as a header file

For example, in the header file.

is defined as follows:

void print(const char * str);

The following is implemented in

void print(const char * str)printf(str);

<>2. Select the file in the new function, then select the C C++ header file, and then enter the header file name you want to use in the file name on the right**h (Preferably in English, and the extension of the file.) h to bring), click to confirm after entering the name, as shown in the figure.

<>4. Find the header file you just created, copy or migrate it to the vc98 include directory under the installation of vc++.

5. Open VC++ again to create a new C language file, as shown in the figure, select the file, select C C++ Source File, and enter the file name**c (Remember to bring the file extension.) c), confirm.

6. Enter ** in the newly created C file, and declare the name of the header file you wrote in the preprocessing command to call the header file library.

For example, in the header file, it is defined as follows:

void print(const char * str);

The following is implemented in

void print(const char * str)printf(str);

1. A function declaration consists of a function return type, a function name, and a list of parameters. The parameter list must include the parameter type, but it does not have to be named. These three elements are called function prototypes, and function prototypes describe the interface of a function.

The programmer who defines the function provides the function prototype, and the programmer who uses the function only needs to prototype the function.

2. For example: [Return Type] Function name (parameter 1 type parameter 1, parameter 2 type parameter 2,......

Example: bool swap(int a, int b);

In this example, the return type of the function is bool, and both arguments are int, one named A and the other named B

Parameter names in function declarations are often ignored, and if they are provided in the declaration, they are only used as supporting documentation. Also, note that the function declaration is a statement, and no semicolons can be left behind!

If you write a function, you need to define the function at the same time as you declare it.

Suppose the header file name is the same file name, the source file name is the same directory.

Add int swap(int a, int b) directly to the header file; This one sentence will do.

Also add include to the source file""

And add the definition of the function:

bool swap(int a,int b)

Note that after declaring in the header file, remember to include this header file in the source file, otherwise you will not find the definition of the function.

Open the project and create a new head file under the project, for example. Then enter **. Then add an include to the end of the include in the main file""That's it.

In this way, the compiler will copy the ** to the main file at compile time (not when the instruction is written) and call it directly. After the compilation is completed, the ** is still stored separately in the file, and the main file only retains the include directive.

Since the function is declared in the header file, it generally refers to the global function, i.e. its scope is the entire program space. If you want to reference the function in another header file, you can do so in two ways:

1) Use include"The name of the header file where the function declaration resides. h"

2) declare using the keyword extern function; Indicates that this is a referenced external function.

For example: the function void windows display(windows t window); The declaration is in the header file, and to be referenced in , you can: (1) include""(2) Add the statement extern void windows display(windows t window);

You can just state the function funca() in it.