C library

A simple C library supporting a number of standard functions. More...

Functions
int	abs (int j)
int	atoi (const char *nptr)
long	atol (const char *nptr)
void	bzero (void *s, size_t n)
int	_doprnt (const char *fmt, va_list ap, int(*putc_func)(int, int), int putc_arg)
int	_doscan (const char *fmt, va_list ap, int(*getch)(int, int), int(*ungetch)(int, int), int arg1, int arg2)
int	fgetc (int dev)
char *	fgets (char *s, int n, int dev)
int	fprintf (int dev, const char *format,...)
int	fputc (int c, int dev)
int	fputs (const char *s, int dev)
void	free (void *ptr)
int	fscanf (int dev, const char *format,...)
long	labs (long j)
void *	malloc (size_t size)
void *	memchr (const void *s, int c, size_t n)
int	memcmp (const void *s1, const void *s2, size_t n)
void *	memcpy (void *dest, const void *src, size_t n)
void *	memset (void *s, int c, size_t n)
int	printf (const char *format,...)
void	qsort (void *base, size_t nmemb, size_t size, int(*compar)(const void *, const void *))
void	srand (unsigned int x)
int	rand (void)
int	sprintf (char *str, const char *format,...)
int	sscanf (const char *str, const char *format,...)
char *	strchr (const char *s, int c)
int	strcmp (const char *s1, const char *s2)
char *	strcpy (char *dest, const char *src)
size_t	strlcpy (char *dest, const char *src, size_t destsize)
size_t	strlen (const char *s)
char *	strncat (char *dest, const char *src, size_t n)
int	strncmp (const char *s1, const char *s2, size_t n)
char *	strncpy (char *dest, const char *src, size_t n)
size_t	strnlen (const char *s, size_t maxlen)
char *	strrchr (const char *s, int c)
char *	strstr (const char *haystack, const char *needle)

Detailed Description

A simple C library supporting a number of standard functions.

Function Documentation

int _doprnt	(	const char *	fmt,
		va_list	ap,
		int(*)(int, int)	putc_func,
		int	putc_arg
	)

Write formatted output.

This is a simplified implementation, and not all standard conversion specifications are supported. A conversion specification (a sequence beginning with the '' character) is divided into 5 parts, the first four of which are optional. The following list explains the features supported by this implementation, broken down by part of the conversion specification:

1. Flags: 0+ of the following:
   • "-" to specify left-justification
   • "0" to specify zero padding
2. Minimum field width: 0-1 of the following:
   • A series of decimal digits not beginning with 0 that specifies the minimum field width as a non-negative integer
   • "*", indicating that the minimum field width is given as an int variadic argument
3. Precision: 0-1 of the following:
   • ".PREC", where PREC is a series of decimal digits that specifies the precision as a non-negative integer
   • "*", indicating that the precision is given as an int variadic argument
4. Length modifier for signed and unsigned integer conversions: 0-1 of the following:
   • "hh" for signed char or unsigned char
   • "h" for signed short or unsigned short
   • "l" for signed long or unsigned long
5. Conversion specifier character: 1 of the following:
   • "\%d" to format a signed integer in decimal (base 10)
   • "\%b" to format an unsigned integer in binary (base 2)
   • "\%o" to format an unsigned integer in octal (base 8)
   • "\%u" to format an unsigned integer in decimal (base 10)
   • "\%x" to format an unsigned integer in lower case hex (base 16)
   • "\%X" to format an unsigned integer in upper case hex (base 16)
   • "\%c" to format a single character
   • "\%s" to format a null-terminated string, or "(null)" for a NULL pointer
   • "\%\%" to format a literal percent sign

If a feature is not mentioned above, assume it is not supported.

Parameters

fmt	Format string.
ap	Variable-length list of values that will be formatted.
putc_func	Character output function. It is passed two arguments; the first will be the character to output, and the second will be putc_arg. It is expected to return EOF on failure.
putc_arg	Second argument to putc_func.

Returns

number of characters written on success, or EOF on failure

int _doscan	(	const char *	fmt,
		va_list	ap,
		int(*)(int, int)	getch,
		int(*)(int, int)	ungetch,
		int	arg1,
		int	arg2
	)

Scan and recognize input according to a format.

This is a minimal implementation and not all standard features are supported. The supported conversion specifications include:

• %s to scan a whitespace-delimited string
• %o to scan an octal number (%O for long)
• %x to scan a hexideminal number (%X for long)
• %c to scan a sequence of characters
• %[ to scan a sequence of characters from the specified set
• %% to match a literal percent sign
• All other conversion specifiers, including %d and %u, are interpreted as specifying a decimal number.
• Whitespace to match any amount of whitespace in the input.
• Maximum length modifier
• 'l' type modifier to parse a long int rather than a normal int
• 'h' type modifier to parse a short int rather than a normal int
• '*' character to suppress assignment

If a feature is not mentioned above, assume it is not supported.

Parameters

fmt	format string for the scan
ap	variable-length list of locations to store the scanned data
getch	Function to get a character. It is expected to return the character as an unsigned char cast to an int on success, or EOF on end-of-file or read error.
ungetch	Function to unget a character. Unlike the standard ungetc(), this is not passed in an explicit character but instead uses the last read character, which will then be expected to be returned on the next getch() call. Only one character of putback needs to be supported.
arg1	First argument to getch and ungetch.
arg2	Second argument to getch and ungetch.

Returns

The number of items successfully matched and assigned, which may be less than the number of format specifiers in the case of a matching failure; alternatively, if EOF or a read error occurs before any matches, EOF is returned.

int abs

(

int

j

)

Calculates the absolute value of an integer.

Parameters

j	The integer to get the absolute value of.

Returns

The absolute value of j. As a special case, if j is INT_MIN, the return value will be undefined because -INT_MIN cannot be represented in an int.

int atoi

(

const char *

nptr

)

Converts the initial portion of an ASCII null-terminated string into an integer. Leading whitespace is skipped and an optional + or - character is allowed to indicate sign. Parsing otherwise stops once the first nondigit character is encountered. If no digits have been encountered at that point, 0 shall be returned.

Parameters

nptr	Pointer to the string to convert.

Returns

The resulting integer.

long atol

(

const char *

nptr

)

Converts the initial portion of an ASCII null-terminated string into a long integer. Leading whitespace is skipped and an optional + or - character is allowed to indicate sign. Parsing otherwise stops once the first nondigit character is encountered. If no digits have been encountered at that point, 0 shall be returned.

Parameters

nptr	Pointer to the string to convert.

Returns

The resulting long integer.

void bzero	(	void *	s,
		size_t	n
	)

Zeroes a block of memory.

Parameters

s	Pointer to the start of the block of memory to zero.
n	Length of the block of memory, in bytes.

int fgetc

(

int

dev

)

Reads a character from a device.

Parameters

dev	Index of device from which to read the character.

Returns

On success, returns the character read as an unsigned char cast to an int. On read error, invalid device, or end-of file, returns EOF.

char* fgets	(	char *	s,
		int	n,
		int	dev
	)

Reads a newline-terminated string from a device.

Parameters

s	The buffer in which to place the resulting data.
n	One less than the maximum number of characters to read.
dev	The index of the device from which to read.

Returns

On success, returns a pointer to the buffer s. On EOF before any characters were read, read error, or invalid device, returns NULL. On success, the resulting buffer will contain a null-terminated string that is the read data up until the first of the next newline, the end of the buffer, or the point at which EOF was reached on the device.

int fprintf	(	int	dev,
		const char *	format,
			...
	)

Writes a formatted message to the specified device.

Parameters

dev	Index of the device to write to.
format	The format string. Not all standard conversion specifications are supported by this implementation. See _doprnt() for a description of supported conversion specifications.
...	Arguments matching those in the format string.

Returns

On success, returns the number of characters written. On write error, returns a negative value.

int fputc	(	int	c,
		int	dev
	)

Writes one character to a device.

Parameters

c	The character to write.
dev	Index of the device to which to write the character.

Returns

On success, returns the character written as an unsigned char cast to an int. On write error or invalid device, returns EOF.

int fputs	(	const char *	s,
		int	dev
	)

Writes a null-terminated string to a device.

Parameters

s	The null terminated string to write.
dev	The device to write the string to.

Returns

A non-negative number on success, or EOF on error.

void free

(

void *

ptr

)

Attempt to free a block of memory based on malloc() accounting information stored in preceding two words.

Parameters

ptr	A pointer to the memory block to free.

int fscanf	(	int	dev,
		const char *	format,
			...
	)

Scan input from a device according to the specified format string.

Parameters

dev	Index of the device from which to scan input.
format	Format string. Not all standard format specifiers are supported by this implementation. See _doscan() for a description of supported conversion specifications.
...	Additional arguments that match those specified in the format string. Generally these need to be a pointer to the corresponding argument so that the value can be set; for example, a %d conversion specifier needs to be matched with an int *.

Returns

The number of items successfully matched and assigned.

long labs

(

long

j

)

Calculates the absolute value of a long integer.

Parameters

j	The long integer to get the absolute value of.

Returns

The absolute value of j. As a special case, if j is LONG_MIN, the return value will be undefined because -LONG_MIN cannot be represented in a long.

void* malloc

(

size_t

size

)

Request heap storage, record accounting information, returning pointer to assigned memory region.

Parameters

size	number of bytes requested

Returns

pointer to region on success, or NULL on failure

void* memchr	(	const void *	s,
		int	c,
		size_t	n
	)

Returns a pointer to the first location in a region of memory at which a particular byte appears.

Parameters

s	A pointer to the memory region to search.
c	The byte to locate.
n	The maximum number of bytes to search.

Returns

A pointer to the first occurrence of c in the memory region, or NULL if c was not found in the memory region.

int memcmp	(	const void *	s1,
		const void *	s2,
		size_t	n
	)

Compares two memory regions of a specified length.

Parameters

s1	Pointer to the first memory location.
s2	Pointer to the second memory location.
n	Length, in bytes, to compare.

Returns

A negative value, 0, or a positive value if the s1 region of memory is less than, equal to, or greater than the s2 region of memory, respectively.

void* memcpy	(	void *	dest,
		const void *	src,
		size_t	n
	)

Copy the specified number of bytes of memory to another location. The memory locations must not overlap.

Parameters

dest	Pointer to the destination memory.
src	Pointer to the source memory.
n	The amount of data (in bytes) to copy.

Returns

dest

void* memset	(	void *	s,
		int	c,
		size_t	n
	)

Fills a region of memory with a byte.

Parameters

s	pointer to the memory to place byte into
c	byte to place
n	length of region to fill, in bytes

Returns

s

int printf	(	const char *	format,
			...
	)

Print a formatted message to standard output.

Parameters

format	The format string. Not all standard format specifiers are supported by this implementation. See _doprnt() for a description of supported conversion specifications.
...	Arguments matching those in the format string.

Returns

On success, returns the number of characters written. On write error, returns a negative value.

void qsort	(	void *	base,
		size_t	nmemb,
		size_t	size,
		int(*)(const void *, const void *)	compar
	)

Sorts an array of data using quicksort. The average-case running time is O(n log n) but the worst case running time is O(n^2).

Parameters

base	Pointer to the array of data to sort.
nmemb	Number of elements in the array.
size	Size of each element in the array, in bytes.
compar	Comparison callback function that is passed pointers to two elements in the array. It must return a negative value, 0, or a positive value if the first element is less than, equal to, or greater than the second element, respectively.

int rand

(

void

)

Generates a pseudorandom integer in the range [0, RAND_MAX]. Beware: this is not re-entrant.

Returns

the random integer

int sprintf	(	char *	str,
		const char *	format,
			...
	)

Write a formatted message to a null-terminated string.

Parameters

str	The output string, which must be large enough to store the formatted result, including the null terminator.
format	The format string. Not all standard conversion specifications are supported by this implementation. See _doprnt() for a description of supported conversion specifications.
...	Arguments matching those in the format string.

Returns

the number of characters written, excluding the null terminator.

void srand

(

unsigned int

x

)

Sets the random seed that will be used in future calls to rand().

Parameters

x	the random seed to set

int sscanf	(	const char *	str,
		const char *	format,
			...
	)

Scan values from a string according to the specified format.

Parameters

str	String from which to read input.
format	Format string. Not all standard format specifiers are supported by this implementation. See _doscan() for a description of supported conversion specifications.
...	Additional arguments that match those specified in the format string. Generally these need to be a pointer to the corresponding argument so that the value can be set; for example, a %d conversion specifier needs to be matched with an int *.

Returns

number of items successfully matched.

char* strchr	(	const char *	s,
		int	c
	)

Returns a pointer to the first location in a null-terminated string at which a particular character appears.

Parameters

s	The string to search.
c	The character to locate.

Returns

The pointer in the string, or NULL if the character was not found.

int strcmp	(	const char *	s1,
		const char *	s2
	)

Compare two null-terminated strings.

Parameters

s1	Pointer to the first string.
s2	Pointer to the second string.

Returns

A negative value, 0, or a positive value if the s1 string is less than, equal to, or greater than the s2 string, respectively.

char* strcpy	(	char *	dest,
		const char *	src
	)

Copies a a null-terminated string to the specified location. The source and destination strings may not overlap.

Parameters

dest	Pointer to the memory to which to copy the string. It must have room for at least the number of characters in the src string, including the null terminator.
src	Pointer to the string to copy.

Returns

A pointer to dest.

size_t strlcpy	(	char *	dest,
		const char *	src,
		size_t	destsize
	)

Copy a null-terminated string into a fixed-size buffer. Unlike strncpy(), this will perform truncation as expected, and the resulting destination string is guaranteed to be null-terminated (unless destsize was 0).

Parameters

dest	Pointer to the buffer into which to copy the string.
src	Pointer to the null-terminated string to copy.
destsize	Size of the dest buffer.

Returns

Length of the src string. This can be tested to detect whether truncation was performed.

size_t strlen

(

const char *

s

)

Calculates the length of a null-terminated string.

Parameters

s	String to calculate the length of.

Returns

Length of the string in bytes, not including the null terminator.

char* strncat	(	char *	dest,
		const char *	src,
		size_t	n
	)

Concatenate at most the specified number of characters from a possibly null-terminated string to another null-terminated string, always null-terminating the result. The strings may not overlap.

Parameters

dest	Pointer to the null-terminated string to which to concatenate the additional string or characters.
src	Pointer to the source string.
n	Maximum number of bytes of the src string to concatenate, excluding the null terminator that will be appended.

Returns

dest

int strncmp	(	const char *	s1,
		const char *	s2,
		size_t	n
	)

Compare two null-terminated strings, examining at most the specified number of bytes.

Parameters

s1	Pointer to the first string.
s2	Pointer to the second string.
n	Maximum number of bytes to compare before returning 0.

Returns

A negative value, 0, or a positive value if the s1 string is less than, equal to, or greater than the s2 string, respectively.

char* strncpy	(	char *	dest,
		const char *	src,
		size_t	n
	)

Copies at most n bytes of a string to a new location. The source string may or may not be null-terminated, but if it is and the null terminator is present in the first n bytes, then copying will stop early when it is reached. If less than n bytes were copied, then the remaining bytes in the destination will be set to null characters until n bytes total have been written.

Beware: if the source string does not contain a null terminator in its first n bytes, the destination will not be null-terminated. To correctly write a null-terminated string into a fixed-size buffer with truncation as expected, consider using strlcpy() instead.

Parameters

dest	Pointer to the memory to which to copy the string.
src	Pointer to the string to copy.
n	Number of bytes to fill (see above description).

Returns

A pointer to dest.

size_t strnlen	(	const char *	s,
		size_t	maxlen
	)

Returns the length of a null-terminated string, but not more than the specified length.

Parameters

s	String to calculate the length of.
maxlen	Maximum length to return.

Returns

Length of the string up to but not including the null terminator, or maxlen if the string is longer than maxlen bytes.

char* strrchr	(	const char *	s,
		int	c
	)

Returns a pointer to the last location in a null-terminated string at which a particular character appears.

Parameters

s	The string to search.
c	The character to locate.

Returns

The pointer in the string, or NULL if the character was not found.

char* strstr	(	const char *	haystack,
		const char *	needle
	)

Returns a pointer to the first location in a null-terminated string at which a particular substring appears.

Parameters

haystack	The string to search.
needle	The string to locate.

Returns

The pointer in the string, or NULL if the string was not found.