C pointer programming path-sixth note

C pointer programming path-sixth note
// Pointer to the file type
// In C language files, you generally use the system's library functions to read and write data.
// File type pointer
// File structure
# Include
# Include
Using namespace std;
Typedef struct
{
Short level; // The degree to which the buffer is full or empty
Unsigned flags; // indicates the File status.
Char fd; // file descriptor
Unsigned hold; // do not read characters without a buffer
Short basize; // buffer size
Unsigned char * buffer; // data buffer location
Unsigned char * curp; // The current pointer
Unsigned istemp; // temporary file
Short token; // used for validity check
} FILE;




// Pointer to the file
FILE * fp;


// Example:
// Enter a character and display it on the screen
# Include
Int main ()
{
Char ch = getchar ();
Putchar ();
Return 0;
}


// The prototype of the scanf () function is
// Int scanf (char const * format ...);
//
// Putchar () function
// The prototype is
// Int putchar (int character)
// Example
# Include
Int main ()
{
Char ch = 'a ';
Puchar (ch); // output character
Putchar ('\ n ');
Putchar ('abc'); // only one character is output
Putchar ('\ 101'); // output character 'a'
Putchar ('\ 015'); // press the Input key without line breaks to move the cursor to the beginning of the line.
Putchar ('\ ''); // output single quotes
Return 0;
}




// File Processing Site
// Function ====/// Function
// Enable or disable fopen () and fclose ();
// Read/write characters fgetc (), fputc ();
// Read/write strings fgets (), fputs ();
// Read/write fread (), fwrite () by data block ()
// Format and read/write fscanf (), fprintf ()
// File fseek (), rewind (), ftell ()
// Determine whether the file ends feof ();
//
// Application example:
# Include
# Include
Using namespace std;
Int main (int argc, char * argv [])
{
// Determine the number of parameters
If (argc! = 3)
{
Printf ("the number of arguments not correct! \ N ");
Exit (1 );
}


FILE * fpr, * fpw;
// Open the source file
If (fpr = fopen (argv [1], 'R') = NULL)
{
Printf ("open source file error! ");
Exit (1 );
}


// Open the target file
If (fpw = fopen (argv [2], 'w') = NULL)
{

Printf ("open destination file error! ");
Exit (1 );
}


Char ch;
// Copy the source file to the target file and read and write one character at a time.
While (ch = fget (fpr ))! = EOF)
{
Fputc (ch, fpw );
}
// Close the source file and target file
Fclose (fpr );
Fclose (fpw );
Return 0;

}

// Merge two integer files in ascending order into one object in ascending order.
# Include
# Include
Using namespace std;


Int main ()
{
FILE * fp1;
FILE * fp2;
FILE * fp3;
Int t1, t2;
If (agrc! = 4)
{
Printf ("The number of arguments not correct! \ N ");
Exit (1 );
}




If (fp1 = fopen (argv [1], "r") = NULL)
{
Printf ("open source file1 error \ n ");
Exit (1 );
}


If (fp2 = fopen (argv [2], "r") = NULL)
{
Printf ("open source file2 error \ n ");
Exit (1 );
}


If (fp3 = fopen (argv [3], "r") = NULL)
{
Printf ("open source file3 error \ n ");
Exit (1 );
}


Fread (& t1, sizeof (int), 1, fp1 );
Fread (& t2, sizeof (int), 2, fp2 );

While (! Feof (fp1 )&&! Feof (fp2 ))
{
If (t1 <t2)
{
Fwrite (& t1.sizeof (int), 1, fp3 );
Fread (& t1, sizeof (int), 1, fp );
}
Else
{
Fwriter (& t2, sizeof (int), 1, fp3 );
Fwriter (& t2, sizeof (int), 1, fp2 );
}
}


While (! Feof (fp1 ))
{
Fwrite (& t1.sizeof (int), 1, fp3 );
Fwrite (& t1, sizeof (int), 1, fp1 );
}


While (! Feof (fp2 ))
{
Fwrite (& t2, sizeof (int), 1, fp3 );
Fwrite (& t2, sizeof (int), 1, fp2 );
}
Fclose (fp1 );
Fclose (fp2 );
Fclose (fp3 );
Return 0;
}