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ANSI LIBRARY : stdio, stdlib, string, math, ctype, time, stdarg, ... _________________________________________________________________________ This section provides a synopsis of functions available in the standard ANSI C library. Here's a list of the ANSI C library header files: <stdio.h> <stdlib.h> <string.h> <math.h> <ctype.h> <time.h> <stdarg.h> <limits.h> <float.h> <assert.h> <setjmp.h> <signal.h> <locale.h> <unix.h> STANDARD INPUT/OUTPUT <stdio.h> _________________________________________________________________________ Filenames are limited to FILENAME_MAX characters. At most FOPEN_MAX files may be open at a given time. CLEARERR void clearerr(FILE *stream) FCLOSE int fclose(FILE *stream) Returns EOF if error occurs, zero otherwise. FEOF int feof(FILE *stream) Returns non-zero if EOF is set. FERROR int ferror(FILE *stream) Returns non-zero if error exists for 'stream'. FFLUSH int fflush(FILE *stream) Returns EOF if error, zero otherwise. fflush(NULL) flushes all output streams. FGETC int fgetc(FILE *stream) Returns EOF if error. FGETS char *fgets(char *s, int n, FILE *stream) Returns s, or NULL if error. FGETPOS int fgetpos(FILE *stream, fpos_t *ptr) Records current position in 'stream' in '*ptr'. FOPEN FILE *fopen(const char *filename, const char *mode) modes: "r" read only "w" write; discard previous contents "a" append "r+" read and write "rb" read (binary) "wb" write (binary) "ab" append (binary) "r+b" read and write (binary) FPRINTF int fprintf(FILE *stream, const char *format, ...) Returns number of characters printed, or negative result if error. Conversion specification begins with '%' and ends with conversion character. In between, there may be (in order): flags: '-' left justify '+' print with sign ' ' <space> prefix with space if no sign '0' <zero> specifies padding with leading zeros '#' alternate output form numbers: n first number specifies field width '.' period used as separator n second number specifies precision (max characters) m modifier (h - short, l - long, L - long double) format characters: d,i int; signed o int; unsigned octal (without leading zero) x,X int; unsigned hexadecimal u int; unsigned c int; single character s char *; string f double; e,E double; scientific notation g,G double; %e or %f format, depending on value p void *; pointer n int *; number of characters written so far % no argument, print '%' example: fprintf( myFilename, "The results are %d and %6.2f\n", myInt, myReal); FPUTC int fputc(int c, FILE *stream) Returns c, or EOF if error. FPUTS int fputs(const char *s, FILE *stream) Returns non-negative result, or EOF if error. FREAD size_t fread(void *ptr, size_t size, size_t nobj, FILE *stream) Reads from 'stream' into 'ptr' at most 'nobj' objects of size 'size'. Returns number of objects read. FREOPEN FILE *freopen(const char *filename, const char *mode, FILE *stream) Returns NULL if error. FSCANF int fscanf(FILE *stream, const char *format, ...) Reads from 'stream' and assigns values through subsequent arguments which must be pointers. Returns EOF if end of file occurs before any conversion; otherwise it returns number of items assigned. Format string should contain conversion specifications consisting of '%' followed by: flag: * suppression; ignore field number: n first number specifies maximum field width width character: h short l long L long double conversion characters: d int * i int *; may be octal (leading 0) or hexadecimal (leading 0x) o int *; octal integer x int *; hexadecimal integer c char *; characters s char *; string of non-white characters e,f float *; could also use 'g' p void *; pointer n int *; writes into arg number of characters read. Nothing read. FSEEK int fseek(FILE *stream, long offset, int origin) Sets file position. Values for origin can be: SEEK_SET beginning SEEK_CUR current position SEEK_END end of file FSETPOS int fsetpos(FILE *stream, const fpos_t *ptr) Positions 'stream' at position recorded by fgetpos. Returns non-zero if error. FTELL long ftell(FILE *stream) Returns current position for 'stream', or -1L if error. FWRITE size_t fwrite(const void *ptr, size_t size, size_t nobj, FILE *stream) Writes from 'ptr' to 'stream' 'nobj' objects of size 'size'. Returns number of objects read. GETC int getc(FILE *stream) Same as fgetc, except a macro. GETCHAR int getchar(void) Equivalent to getc(stdin). GETS char *gets(char *s) Returns s, or NULL if error. PERROR void perror(const char *s) Prints error message 's'. PRINTF int printf(const char *format, ...) Equivalent to fprintf(stdout, ...) PUTC int putc(int c, FILE *stream) Same as fputc, except a macro. PUTCHAR int putchar(int c) Equivalent to putc(c, stdout). PUTS int puts(const char *s) Returns non-negative result, or EOF if error. REMOVE int remove(cost char *filename) Returns non-zero if attempt to delete file fails. RENAME int rename(const char *oldname, const char *newname) Returns non-zero if attempt to rename file fails. REWIND void rewind(FILE *stream) SCANF int scanf(const char *format, ...) Identical to fscanf(stdin, ...) SPRINTF int sprintf(char *s, const char *format, ...) Same as printf except output written to string 's'. SSCANF int sscanf(char *s, const char *format, ...) Equivalent to scanf(...) except input is taken from 's'. SETBUF void setbuf(FILE *stream, char *buf) If 'buf' is NULL, buffering is turned off, otherwise equivalent to 'void setvbuf(stream, buf, _IOFBF, BUFSIZE)'. SETVBUF int setvbuf(FILE *stream, char *buf, int mode, size_t size) Returns non-zero if error. A value of NULL for 'buf' allocates buffer. modes: _IOFBF full buffering _IOLBF line buffering _IONBF no buffering TMPFILE FILE *tmpfile(void) Returns NULL if error. TMPNAM char *tmpnam(char s[L_tmpnam]) tmpnam(NULL) creates unique filename. TMP_MAX different names guaranteed. UNGETC int ungetc(int c, FILE *stream) pushes 'c' (converted to an unsigned char) back onto 'stream'. Returns 'c' or EOF if error. VPRINTF int vprintf(const char *format, va_list arg) VFPRINTF int vfprintf(FILE *stream, const char *format, va_list arg) VSPRINTF int vsprintf(char *s, const char *format, va_list arg) STANDARD LIBRARY <stdlib.h> _________________________________________________________________________ ABORT void abort(void) Causes program to abnormally terminate. ABS int abs(int n) ATEXIT int atexit(void (*fcn)(void)) Registers function to be called when program terminates. Returns non-zero if error. ATOF double atof(const char *s) ATOI int atoi(const char *s) ATOL long atol(const char *s) BSEARCH void *bsearch(const void *key, const void *base, size_t n, size_t size, int (*cmp)(const void *keyval, const void *datum)) CALLOC void *calloc(size_t nobj, size_t size) DIV div_t div(int num, int denom) EXIT void exit(int status) Causes normal program termination. FREE void free(void *p) Deallocates spaced pointed to by 'p'. Returns NULL if error. GETENV char *getenv(const char *name) LABS long labs(long n) LDIV ldiv_t ldiv(long num, long denom) MALLOC void *malloc(size_t size) Returns pointer for object of size 'size', or NULL if request for memory denied. MBLEN int mblen(const char *s, size_t n) Multi-byte function. Returns number of bytes of character s. MBSTOWCS size_t mbstowcs(wchar_t *pwcs, const char *s, size_t n) Multi-byte function. Copies elements of s to pcws, stopping after it copies n elements or a NULL character. Returns number of characters copied. MBTOWC int mbtowc(wchar_t *pwc, const char *s, size_t n) Multi-byte function. Sets pwc to the first element of s if s is not NULL and n is not zero. Returns 1 if successful, zero if s is NULL, and -1 if n is zero. QSORT void qsort(void *base, size_t n, size_t size, int (*cmp)(const void *, const void *)) RAND int rand(void) Returns pseudo-random integer between 0 and RAND_MAX. REALLOC void *realloc(void *p, size_t size) STRTOD double strtod(const char *s, char **endp) STRTOL long strtol(const char *s, char **endp, int base) STRTOUL unsigned long strtoul(const char *s, char **endp, int base) SRAND void srand(unsigned int seed) SYSTEM int system(const char *s) If system provides a command processor, executes command line in s. If s is NULL and there is a command processor, returns non-zero value, otherwise returns zero. WCSTOMBS size_t wcstombs(wchar_t *pwcs, const char *s, size_t n) Multi-byte function. Copies elements of pwcs to s, stopping after it copies n elements or the NULL character. Returns the number of characters copied. WCTOMB int wctomb(char *s, wchar_t wchar) Multi-byte function. Sets first element of s to wchar if s is not NULL. STRING FUNCTIONS <string.h> _________________________________________________________________________ MEMCHR void *memchr(const char *cs, int c, size_t n) Returns first occurrence of character 'c' in 'cs' or NULL. MEMCMP int memcmp(const char *cs, const char *ct, size_t n) Compares 'n' characters of 'cs' with 'ct'. MEMCPY void *memcpy(char *s, const char *ct, size_t n) Copy 'n' characters from 'ct' to 's', returns 's'. MEMMOVE void *memmove(char *s, const char *ct, size_t n) Same as 'memcpy'. Works if objects overlap. MEMSET void *memset(char *s, int c, size_t n) Put character 'c' into first 'n' characters of 's', returns 's'. STRCAT char *strcat(char *char *s, const char *ct) Concatenates 'ct' to 's', returns 's'. STRCHR char *strchr(const char *cs, int c) Returns pointer to first occurrence of 'c' in 'cs' or NULL. STRCMP int strcmp(const char *cs, const char *ct) Returns zero if cs == ct. STRCOLL int strcoll(const char *cs, const char *ct) Compare strings based on locale environment. Equivalent to strcmp. STRCPY char *strcpy(char *s, const char *ct) Copies 'ct' to 's', including '\0', returns 's'. STRCSPN size_t strcspn(const char *cs, const char *ct) STRERROR char *strerror(n) Returns pointer to string defining error 'n'. STRLEN size_t strlen(const char *cs) Returns length of 'cs'. STRNCAT char *strncat(char *s, const char *ct, size_t n) STRNCMP int strncmp(const char *cs, const char *ct, size_t n) Returns zero if 'n' characters of both strings are equal. STRNCPY char *strncpy(char *s, const char *ct, size_t n) STRPBRK char *strpbrk(const char *cs, const char *ct) Return pointer to first occurrence of any character in 'ct' or NULL. STRRCHR char *strrchr(const char *cs, int c) Returns pointer to last occurrence of 'c' in 'cs' or NULL. STRSPN size_t strspn(const char *cs, const char *ct) STRSTR char *strstr(const char *cs, const char *ct) Returns pointer to first occurrence of string 'ct' in 'cs' or NULL. STRTOK char *strtok(char *s, const char *ct) Searches 's' for tokens delimited by characters from 'ct'. Returns NULL when no further tokens found. STRXFRM size_t strxfrm(char *cs, const char *ct, size_t n) Copies the first n characters of ct into cs. If n is zero, cs can be NULL. Equivalent to strncpy except strxfrm returns length of ct. MATH FUNCTIONS <math.h> _________________________________________________________________________ In the following list, 'x' and 'y' are type 'double', n is type 'int'. All angles for trigonometric functions are in radians. sin(x) cos(x) tan(x) asin(x) acos(x) atan(x) atan2(y,x) sinh(x) cosh(x) tanh(x) exp(x) log(x) log10(x) pow(x,y) sqrt(x) ceil(x) floor(x) fabs(x) ldexp(x,n) frexp(x, int *exp) modf(x, double *ip) fmod(x,y) CHARACTER TESTS <ctype.h> _________________________________________________________________________ All functions in <ctype.h> take a character and return an 'int' which represents a true (non-zero) or false (zero) result. isalnum(int c) alpha-numeric character isalpha(int c) upper or lower-case letter iscntrl(int c) control character isdigit(int c) decimal digit isgraph(int c) !space islower(int c) lower-case isprint(int c) printing character, including space ispunct(int c) !(space || letter || digit) isspace(int c) space, tab, newline isupper(int c) upper-case isxdigit(int c) hexadecimal digit tolower(int c) converts and returns lowercase letter toupper(int c) converts and returns uppercase letter DATA AND TIME FUNCTIONS <time.h> _________________________________________________________________________ Many functions in <time.h> utilize a data structure which has the following format: struct tm { int tm_sec; int tm_min; int tm_hour; int tm_mday; int tm_mon; int tm_year; int tm_wday; int tm_yday; int tm_isdst; // Daylight Savings Time flag }; ASCTIME char *asctime(const struct tm *tp) Converst time into standard string; "Fri May 26 19:27:30 1995\n". CLOCK clock_t clock(void) Returns processor time used by the program. CTIME char *ctime(const time_t *tp) Converts calendar time to local time. DIFFTIME double difftime(time_t time2, time_t time1) Returns difference in two times in seconds. GMTIME struct tm *gmtime(const time_t *tp) Converts calendar time into Coordinated Universal Time (UTC). LOCALTIME struct tm *localtime(const time_t *tp) Converts calendar time into local time. MKTIME time_t mktime(struct tm *tp) Converts local time to calendar time. STRFTIME size_t strftime(char *s,size_t smax,const char *fmt,const struct tm *tp) Formats date and time data from *tp into string 's'. Available formats include: %a abbriviated weekday name %A full weekday %b abbreviated month %B full month %c date and time %d day of month (01-31) %H hour (24 hr) %I hour (12 hr) %j day of year %m month %M minute %p AM or PM %S second %U week number (Sunday 1st day of week) %w weekday (0-6) %W week number (Monday 1st day of week) %x date %X time %y year without century %Y century %Z time zone name %% % TIME time_t time(time_t *tp) Returns current calendar time. If 'tp' is not NULL, return value is also assigned to 'tp'. VARIABLE ARGUMENT LISTS <stdarg.h> _________________________________________________________________________ Use the functions in <stdarg.h> to retrieve arguments from a variable length function argument list. An example of using variable argument lists can be found in Section 'Functions'. Before using functions, you must declare a variable of type 'va_list' as follows: va_list ap; You then use the 'va_start' macro to initialize. Afterwords, each subsequent call to 'va_arg' returns the next argument. Finally, call 'va_end'. VA_START void va_start(va_list ap, lastarg) Provide the last argument in a variable length function list as 'lastarg' to initialize va_list variable. VA_ARG type va_arg(va_list ap, type) Returns next argument in variable length function list. You must supply the data type in 'type'. va_arg returns type specified in 'type'. VA_END void va_end(va_list ap) Execute after arguments have been processed, but prior to exiting function. IMPLEMENTATION SPECIFICS <limits.h> and <float.h> _________________________________________________________________________ The following constants are defined in <limits.h>: CHAR_BIT CHAR_MAX CHAR_MIN INT_MAX INT_MIN LONG_MAX LONG_MIN SCHAR_MAX SCHAR_MIN SHRT_MAX SHRT_MIN UCHAR_MAX UINT_MAX ULONG_MAX USHRT_MAX The following constants are defined in <float.h>: FLT_RADIX FLT_ROUNDS FLT_DIG FLT_EPSILON FLT_MANT_DIG FLT_MAX FLT_MAX_EXP FLT_MIN FLT_MIN_EXP DBL_DIG DBL_EPSILON DBL_MANT_DIG DBL_MAX DBL_MAX_EXP DBL_MIN DBL_MIN_EXP DIAGNOSTICS <assert.h> _________________________________________________________________________ ASSERT void assert(int expr) If 'expr' is zero, prints error message on stderr. If NDEBUG is defined, assert macro is ignored. NON-LOCAL JUMPS <setjmp.h> _________________________________________________________________________ SETJMP int setjmp(jmp_buf env) Saves state information for later use by 'longjmp'. LONGJMP void longjmp( jmp_buf env, int val) Restores state saved by most recent call to setjmp. Execution resumes as if the setjmp function had just executed and returned the non-zero value val. Function containing setjmp must not have terminated. SIGNALS <signal.h> _________________________________________________________________________ SIGNAL void (*signal(int sig, void (*handler)(int)))(int) Calls function pointed to by handler with argument of the type of signal. SIG_DFL default behavior: handler ignored SIG_IGN ignore signal: handler ignored SIGABRT abnormal termination SIGFPE arithmetic error SIGILL illegal instruction SIGINT interrupt SIGSEGV illegal storage access SIGTERM termination request RAISE int raise( int sig ) Sends the signal 'sig' to the program, returns non-zero if unsuccessful. LOCALE <locale.h> _________________________________________________________________________ LOCALECONV struct lconv *localeconv(void) Returns structure of formatting requirements according to the rules of the current locale. SETLOCALE char *setlocale(int category, const char *locale) Sets locale environment. The parameter category can be one of the following: LC_ALL LC_COLLATE LC_TYPE LC_MONETARY LC_NUMERIC LC_TIME UNIX <unix.h> _________________________________________________________________________ FSTAT int fstat(int fn, struct stat *statptr) Returns file information into statptr data structure. Returns zero if successful. PUTW int putw(int word, FILE *stream) Writes word to stream. Returns word is successful, EOF if not. STAT int stat(char *filename, struct stat *statptr) Returns file information about filename into statptr data structure. Returns zero if successful. 
