editv1.c

Software Development in C: A Practical Approach to Programming and Design 软件开发：编程与设计（C））——国外经典教材·计

//---------------------------------------------------------
/*
File Name:	EditV1.C

Remarks:	This is the first version of what will become 
			a text editor. 
*/


//---------------------------------------------------------
// Include Files
//---------------------------------------------------------

#include <stdio.h>

// End Include Files---------------------------------------



//---------------------------------------------------------
// Constants
//---------------------------------------------------------

const int MAX_BUFFER_ROWS 		= 100;
const int MAX_BUFFER_COLS 		= 60;
const int DISPLAY_AREA_SIZE   	= 20;
const int SCREEN_SIZE			= 25;

// End Constants-------------------------------------------




int main()
{
	char textBuffer[MAX_BUFFER_ROWS][MAX_BUFFER_COLS];
	int i,j;
	char tempChar;
	int top;

	// Fill the buffer with characters.
	// For each row...
	for (i=0,tempChar=' ';i<MAX_BUFFER_ROWS;i++)
	{
		// For each column...
		for (j=0;j<MAX_BUFFER_COLS-1;j++)	
		{
		      	// Store a character in the buffer.
			textBuffer[i][j]=tempChar++;

			// If tempChar was incremented past z...
			if (tempChar>'z')
			{
				// Reset tempChar to  space.
				tempChar=' ';
			}
		}	
		textBuffer[i][MAX_BUFFER_COLS-1]='\0';
	}

	// While the user doesn't what to quit...
	top=0;
	for (tempChar=' ';
		 (tempChar!='q') && (tempChar!='Q');
		 scanf("%c",&tempChar))
	{
		// Scroll the screen up or down based on user input.
		switch (tempChar)
		{
			case 'U':
			case 'u':
				top -= DISPLAY_AREA_SIZE-1;
			break;

			case 'D':
			case 'd':
				top += DISPLAY_AREA_SIZE-1;
			break;
		}

		/* If the index of the first line of text to be 
		displayed is now outside the boundaries of the 
		array, adjust it so that it is inside. */
		if (top<0)
		{
			top=0;
		}
		else if (top >= MAX_BUFFER_ROWS)
		{
			top=MAX_BUFFER_ROWS-DISPLAY_AREA_SIZE;
		}

		// Clear the screen.
		for (i=0;i<SCREEN_SIZE;i++)	// For each row...
		{
			// Print an endline.
		    printf("\n");
		}

		// For each row of text...
		for (i=top,j=0;
			  (i < top+DISPLAY_AREA_SIZE) && 
				(i < MAX_BUFFER_ROWS);
			  i++,j++)
		{
			printf("%s\n",textBuffer[i]);
		}

		// Display a status line.
		if (top==0)
		{
			printf("\nBeginning of buffer\n");
		}
		else if (top+DISPLAY_AREA_SIZE>=MAX_BUFFER_ROWS)
		{
			printf("\nEnd of buffer\n");
		}
		else
		{
			printf("\n\n");
		}

	      	// Prompt the user for a command.
		printf("COMMAND:");
	}


	return (0);
}

//-------------------end EditV1.C--------------------------