tstring.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:	Tstring.c
Comments:	This file contains the implementation of the 
			text_string type.
*/

//---------------------------------------------------------
// Include files

#include <stdio.h>
#include "Tstring.h"

// End include files
//---------------------------------------------------------



//---------------------------------------------------------
/*
Function:		TextStringInitString

Parameters
	Input:		theString - Contains the text_string to be 
					initialized.
	Output:		theString - Contains the initialized 
					text_string.

Return Values:	This function does not return a value.

Comments:		Before a text_string variable is used, it 
				must be initialized by this function. Your
				program must supply a text_string variable
				in the paramter list. This function will
				set all of the character locations in the
				parameter to the null character. Therefore,
				theString is both an input and output 
				parameter.
*/

void TextStringInitString(text_string theString)
{
	int i;

	for (i=0;i<TEXT_STRING_MAX_LENGTH;i++)
	{
		theString[i] = '\0';
	}
}

// End TextStringInitString
//---------------------------------------------------------




//---------------------------------------------------------
/*
Function:		TextStringSetString

Parameters
	Input:		charArray - Contains an array of characters
					which will be copied into theString.
	Output:		theString - Specifies a text_string into
					which the characters from charArray
					will be copied.

Return Values:	Upon success, this function returns the 
				value TSE_NO_ERROR. If charArray is empty,
				it returns TSE_EMPTY_SOURCE_CHAR_ARRAY. If
				there are too many characters in charArray
				to copy into theString, this function 
				returns TSE_SOURCE_CHAR_ARRAY_TOO_LONG.

Comments:		This function copies characters from the
				input parameter charArray to the output 
				parameter theString. 
*/

text_string_error TextStringSetString(
						text_string theString,
					    char charArray[])
{
	int i;
	text_string_error errorStatus = TSE_NO_ERROR;

	// Copy the characters in the array to the text_string.
	// Insert a for loop here.

	// If the source array was empty...
	if (i==0)
	{
		// Set a warning.
		errorStatus = TSE_EMPTY_SOURCE_CHAR_ARRAY;
	}
	// Else if the source array was too long...
	else if (i>=TEXT_STRING_MAX_LENGTH)
	{
		// Set an error.
		errorStatus = TSE_SOURCE_CHAR_ARRAY_TOO_LONG;
	}
	// Else the source array was copied ok...
	else
	{
		// Append a null character on the end.
		theString[i]='\0';
	}

	return (errorStatus);
}

// End TextStringSetString
//---------------------------------------------------------




//---------------------------------------------------------
/*
Function:		TextStringSetCharacter

Parameters
	Input:		theCharacter - Contains a character which 
					will be copied into theString.
				characterIndex - Specifies the index number
					of the character position in theString
					where theCharacter will be copied into.
					Index numbers begin with 0.
	Output:		theString - Specifies a text_string into
					which the character will be copied.

Return Values:	Upon success, this function returns the 
				value TSE_NO_ERROR. If index number is out
				of range, it returns TSE_INDEX_OUT_OF_RANGE.
				If index number is after then end of the 
				string, this function returns 
				TSE_INDEX_AFTER_END_OF_STRING.

Comments:		This function copies a character into the 
				output parameter theString. It is possible 
				for theString to contain less than the 
				maximum number of characters. If it does,
				and the index number is within range but 
				after the end of the string, this function
				returns an error.
*/

text_string_error TextStringSetCharacter(
						text_string theString,
						char theCharacter,
						int characterIndex)
{
	text_string_error errorStatus = TSE_NO_ERROR;
	int length;

	// If the index is out of range...
	if ((characterIndex < 0) || 
		(characterIndex>=TEXT_STRING_MAX_LENGTH-1))
	{
		// Set an error.
		errorStatus = TSE_INDEX_OUT_OF_RANGE;
	}
	else
	{
		// Find the current length of the text_string.
		for (length = 0;
			 (length<TEXT_STRING_MAX_LENGTH-1) && 
				 (theString[length]!='\0');
			 length++)
		{
			/* The body is empty. The counting is done in
			the control portion of the for loop. */
		}

		/* If the character index is after the end 
		of the string... */
		if (characterIndex>=length)
		{
			// Set an error.
			errorStatus = TSE_INDEX_AFTER_END_OF_STRING;
		}
		else
		{
			// Set the character.
			theString[characterIndex]=theCharacter;
		}
	}

	return (errorStatus);
}

// End TextStringSetCharacter
//---------------------------------------------------------



//---------------------------------------------------------
/*
Function:		TextStringGetCharacter

Parameters
	Input:		
	Output:		

Return Values:	

Comments:		
*/

int TextStringGetCharacter(text_string theString,
 						   int characterIndex)
{
	int length;
	int theCharacter = -1;

	// If the index is in range...
	{
		// Find the current length of the text_string.
		
		/* If the index is not beyond the end of the 
		string... */
			// Get the character.
	}

	return (theCharacter);
}

// TextStringGetCharacter
//---------------------------------------------------------




text_string_error TextStringAppendCharacter(
						text_string theString,
						char theCharacter)
{
	text_string_error errorStatus = TSE_NO_ERROR;
	int length;

	// Find the position of the null character.

	// If the string is full...
	{
		// Set an error
	}
	else
	{
		// Append the character.
		// Put the null character on the end.
	}
	return (errorStatus);
}


int TextStringPrintString(text_string theString)
{
	return (printf("%s",theString));
}