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Программирование

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Advanced C 1992

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Part IV • Documenting the Differences

tmpfile()

Header:	stdio.h
Syntax:	FILE * tmpfile(void);
Description:	Creates a temporary work file and opens it for update. This file is
	removed by the system either when it is closed or the program
	ends.
Parameters:	None.
Returns:	Handle to a file or NULL if the function fails.
Example:	FILE * TempWork = tmpfile();
Note:	Be careful not to close the file in error because this removes the
	file.

tmpnam()

Header:	stdio.h
Syntax:	char * tmpnam(char * szFileName);
Description:	Creates a save name for a temporary work file. This function is
	used when tmpfile() cannot be used, such as in situations where
	the file must be closed for some reason.
Parameters:	szFileName—Pointer to a buffer to hold the filename. This buffer
	must be at least L_tmpnam characters long.
Returns:	Pointer to the filename buffer. If szFileName is NULL, then the
	buffer is a static internal buffer.
Example:	char	szBuffer[L_tmpnam];

tmpnam(szBuffer);

printf(“The temporary work file is ‘%s’\n”, szBuffer);

Note: Don’t forget to remove the file when the program ends.

596

	ANSI C’s Library Function	C C C
		14C
		C C C
tolower()		C C
tolower()
Header:	ctype.h & stdlib.h
Syntax:	int tolower(int chChar);
Description:	Converts chChar to lowercase if it was originally uppercase. If
	chChar was not uppercase, then it is returned unchanged.
Parameters:	chChar—Uppercase letter to be converted to lowercase.
Returns:	The character converted to lowercase.
Example:	printf(“‘A’ in lowercase is ‘%c’\n”,
	tolower(‘A’);
	/* Will print ‘A’ in lowercase is ‘a’ */
Note:	See toupper().
toupper()
Header:	ctype.h & stdlib.h
Syntax:	int toupper(int chChar);
Description:	Converts chChar to uppercase if it was originally lowercase. If
	chChar was not lowercase, then it is returned unchanged.
Parameters:	chChar—Lowercase letter to be converted to uppercase.
Returns:	The character converted to uppercase.
Example:	printf(“‘a’ in uppercase is ‘%c’\n”,
	toupper(‘a’);
	/* Will print ‘a’ in uppercase is ‘A’ */
Note:	See tolower().
ungetc()
Header:	stdio.h
Syntax:	int ungetc(int chChar, FILE * OpenFile);

597

Part IV • Documenting the Differences

Description:	This function pushes back a character to the file OpenFile (which
	was opened for input).
Parameters:	chChar—Character to be pushed back to the file.
	OpenFile—Pointer to an opened file.
Returns:	The character that was pushed back.
Example:	char	szBuffer[129];

	printf(“Please press the ‘b’ key: “);
	szBuffer[0] = (char)getc(stdin);
	ungetc(‘A’, stdin);
	szBuffer[1] = (char)getc(stdin);
	printf(“szBuffer has %2.2s\n”, szBuffer);
	/* Will print szBuffer has bA (if you type a ‘b’
	at the prompt) */
Note:	The character need not be the same one as was last read. You may
	ungetc() only one character before the character is read or
	discarded (by a call to fseek(), fsetpos(), or rewind()).

va_arg()

Header:	stdarg.h
Syntax:	type va_arg(va_list param, type);
Description:	Obtains the next argument from a list of variable arguments to a
	function.
Parameters:	param—Parameter list pointer.
	type—Type of the next (to be fetched) parameter.
Returns:	Value of the parameter being fetched.
Example:	/* Program VARGS, written 17 June 1999 by Peter D.

598

ANSI C’s Library Function

Hipson */

#include <limits.h> #include <stdarg.h> #include <stdio.h> #include <stdlib.h>

#define	TRUE	1
#define	FALSE	(!TRUE)
int	AddList(int nFirst, ...);
int	OurErrors(char * OutputFormat, ...);
void	main()
{
int	nSum;

nSum = AddList(10, 20, 30, 40, 50, 60, 70, 80, 90, INT_MIN);

(void)OurErrors(“%s - %d, %s\n”, “First”, nSum, “Second”);

}

int AddList(

int nFirst,

...)

{

int	nReturnValue = nFirst;
int	nThisValue;

va_list Arguments;

va_start(Arguments, nFirst);

C C C

C14C C

C C C

599

Part IV • Documenting the Differences

while((nThisValue = va_arg(Arguments, int)) !=

INT_MIN)

{

		nReturnValue += nThisValue;
		}
		va_end(Arguments);
		return(nReturnValue);
	}
	int	OurErrors(
		char * OutputFormat,
		...)
	{
	va_list Arguments;
		va_start(Arguments, OutputFormat);
		vfprintf(stderr, OutputFormat, Arguments);
		va_end(Arguments);
		return(0);
	}
Note:	See Chapter 13, “All About Header Files,” for more information.
va_end()
Header:	stdarg.h
Syntax:	void va_end(va_list param);
Description:	Ends the processing of the variable number of arguments.

600

	ANSI C’s Library Function	C C C
		14C
		C C C
Parameters:	param—Variable argument list.	C C
Parameters:	param—Variable argument list.
Returns:	No return value.
Example:	(See va_arg(), preceding function described.)
Note:	See Chapter 13, “All About Header Files,” for more information.
va_start()
Header:	stdarg.h
Syntax:	void va_start(va_list param, previous);
Description:	Starts processing of a variable number of arguments.
Parameters:	param—va_list variable, used by the va_ functions.
	previous—Name of the last fixed parameter being passed to the
	called function.
Returns:	No return value.
Example:	(See va_arg(), previously described.)
Note:	See Chapter 13, “All About Header Files,” for more information.
vfprintf()
Header:	stdio.h
Syntax:	int vfprintf(FILE * OpenFile, const char *
	szFormat, va_list VarArgs);
Description:	Prints to the specified file by using arguments passed by another
	function.
Parameters:	OpenFile—Pointer to an opened file.
	szFormat—Pointer to a string containing format information.
	VarArgs—Variable argument list.
Returns:	Number of characters written or a negative value if there was an
	error.

601

Part IV • Documenting the Differences

Example:	/* Program VARGS, written 17 June 1999 by
	Peter D. Hipson */
	#include <limits.h>
	#include <stdarg.h>
	#include <stdio.h>
	#include <stdlib.h>
	int	OurErrors(char * OutputFormat, ...);
	void	main()
	{
	int	nSum = 100;
		(void)OurErrors(“%s - %d, %s\n”,
		“First”, nSum, “Second”);
	}
	int	OurErrors(
		char * OutputFormat,
		...)
	{
	va_list Arguments;
		va_start(Arguments, OutputFormat);
		vfprintf(stderr, OutputFormat,
		Arguments);
		va_end(Arguments);
		return(0);
	}
Note:	See vprintf().

vprintf()

Header: stdio.h

Syntax: int vprintf(const char * szFormat, va_list

VarArgs);

602

		ANSI C’s Library Function	C C C
			14C
			C C C
Description:			C C
Description:	Prints to stdout using arguments passed by another function.
Parameters:	szFormat—Pointer to a string containing format information.
	VarArgs—Variable argument list.
Returns:	Number of characters written or a negative value if there was an
	error.
Example:	/* Program VARGS, written 17 June 1992 by
	Peter D. Hipson */
	#include <limits.h>
	#include <stdarg.h>
	#include <stdio.h>
	#include <stdlib.h>
	int	OurOutput(char * OutputFormat, ...);
	void	main()
	{
	int	nSum = 100;
		(void)OurOutput(“%s - %d, %s\n”,
		“First”, nSum, “Second”);
	}
	int OurOutput(
		char * OutputFormat,
		...)
	{
	va_list Arguments;
		va_start(Arguments, OutputFormat);
		vprintf(OutputFormat, Arguments);
		va_end(Arguments);
		return(0);
	}
Note:	See vfprintf().

603

Part IV • Documenting the Differences

vsprintf()

Header:	stdio.h
Syntax:	int vsprintf(char * szBuffer, const char *
		szFormat, va_list VarArgs);
Description:	Prints, using arguments passed by another function, to the buffer
	pointed to by szBuffer.
Parameters:	szBuffer—Pointer to a buffer to write to.
	szFormat—Pointer to a string containing format information.
	VarArgs—Variable argument list.
Returns:	Number of characters written or a negative value if there was an
	error.
Example:	/* Program VARGS, written 17 June 1992 by
	Peter D. Hipson */
	#include <limits.h>
	#include <stdarg.h>
	#include <stdio.h>
	#include <stdlib.h>
	int	OurOutput(char * OutputBuffer,
		char * OutputFormat, ...);
	void	main()
	{
	char	szBuffer[100];
	int	nSum = 100;
		(void)OurOutput(szBuffer,
		“%s - %d, %s\n”,
		“First”, nSum, “Second”);
		printf(“%s”, szBuffer);
	}
	int	OurOutput(
		char * OutputBuffer,

604

ANSI C’s Library Function

char * OutputFormat,

...)

{

va_list Arguments;

va_start(Arguments, OutputFormat);

vsprintf(OutputBuffer, OutputFormat, Arguments);

va_end(Arguments);

return(0);

}

Note: See vfprintf() and vprintf().

wcstombs()

C C C

C14C C

C C C

Header: stdlib.h

Syntax: size_t wcstombs(char * szDestination,

const wchar_t * pWideChars, size_t nSize);

Description: Converts the wide characters in the buffer pointed to by pWideChars to multibyte characters. Stores up to nSize characters

in szDestination.

Parameters: szDestination—Pointer to a buffer to receive the multibyte characters.

pWideCharacters—Pointer to a buffer containing the wide characters to be converted.

nCount—Size of szDestination.

Returns: Number of characters converted.

Example: wcstombs(szBuffer, szWideChars,

sizeof(szBuffer));

Note:

See wctomb().

605

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