Advanced C 1992

Header:

malloc.h & stdlib.h

Syntax:

void * malloc(size_t SizeToAllocate);

Description:

Allocates memory (uninitialized).

Parameters:

SizeToAllocate—Size of the memory block to allocated.

Returns:

Pointer to the memory block allocated or NULL if the memory

could not be allocated..

Example:

int * nArray;

Header:

stdlib.h

Syntax:

int mblen(const char * szString, size_t

nCount);

by szString, looking for the number of bytes in the next multibyte

character.

Parameters:

szString—Pointer to the first byte of the multibyte character.

Returns:

Zero if szString is NULL, -1 if this is not a multibyte character or

the number of characters in the multibyte character.

Example:

int nCount;

nCount = mblen(szString, 3);

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pBuffer2—Pointer to the second buffer.

nLength—Number of bytes to compare.

Returns:

Zero if they are equal, < 0 if pBuffer1 is less than pBuffer2,

or > 0 if pBuffer1 is greater than pBuffer2.

Example:

char

char

/* Will not print since the strings are not

equal */

the string is a NULL terminated character string.

Syntax:

void * memcpy(void * pDestination, const

destination must not overlap.

Parameters:

pDestination—Pointer to the destination buffer.

pSource—Pointer to the source buffer.

nLength—Number of bytes to copy.

Header:

string.h

Syntax:

void * memmove(void * pDestination, const

void * pSource, size_t

nLength);

destination may overlap.

Parameters:

pDestination—Pointer to the destination buffer.

pSource—Pointer to the source buffer.

nLength—Number of bytes to copy.

Returns:

The pointer pDestination.

Example:

char

szString1[100] = {“Now is all the

time for all good

men”};

char

szString2[100] = {“Now is not the

time for all good

men”};

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used where the source and destination overlap, while memmove()

works correctly when there is overlap; however, this function may

be slower.

Syntax:

void * memset(void * pBuffer, int nByte,

Parameters:

pBuffer—Buffer that is to be filled.

nByte—Byte to fill the buffer with.

nLength—How many bytes to fill.

Returns:

The pointer pBuffer.

Example:

int

/* Zeros out the allocated array */

data objects, which are not otherwise initialized.

Syntax:

time_t mktime(struct tm * Time);

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Member);

Structure.

Member—A member in Structure.

Returns:

Offset in bytes.

Example:

struct tm Time;

printf(“the offset of tm_year is %d”,

offsetof(struct tm, tm_year));

name.

Syntax:

void perror(const char * szPrefix);

Description:

Prints an error message corresponding to errno to stderr. If

szPrefix is not NULL, that string is prefixed to the message

printed.

Parameters:

Returns:

Zero if successful, otherwise a non-zero value.

Example:

/* Set errno to an error value (usually set by a library

function) */

errno = EACCES;

perror(“DUMMY ERROR HERE”);

/* prints: DUMMY ERROR HERE: Permission denied

*/

Header:

stdio.h

Syntax:

int printf(const char * szFormat, ...);

Description:

Prints, to stdout formatted output as defined by szFormat.

Parameters:

szFormat—A format descriptor string.

Returns:

Number of characters written. If negative, then an error occurred.

Example:

printf(“The number one is %d\n”, 1);

Note:

See the section on printf() format codes at the end of this

chapter.

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OpenFile—Pointer to an opened file.

Returns:

Character nChar if successful, otherwise EOF.

Example:

putc(‘A’, stdout);

Note:

Same as fputc() except that putc() can be implemented as a

macro.

Syntax:

int putchar(int nChar);

Description:

Writes nChar to the stream file stdout.

Parameters:

nChar—Character to be written.

Returns:

Character nChar if successful, otherwise EOF.

Example:

putchar(‘A’);

Note:

Same as fputc(nChar, stdout) except that putc() can be imple-

mented as a macro.

Syntax:

int puts(const char * szString);

Description:

Writes szString to the stream file stdout.

Parameters:

szString—Pointer to the character string to be written.

Returns:

Non-zero positive value if successful, otherwise EOF.

Example:

putchar(“Now is the time.\n”);

Note:

Also see fputs() and putc().