C Standard Library – <stdlib.h>

May 11, 2021 C

1. C Standard Library - slt;stdlib.h.gt;

2. Brief introduction

3. Library variables

4. Library macros

5. The library function

C Standard Library - slt;stdlib.h.gt;

Brief introduction

The stdlib .h header file defines four variable types, some macros, and various common tool functions.

Library variables

Here are the types of variables defined in the header file stdlib.h:

Serial number	Variable & description
1	size_t This is an unsigned integer type, it is sizeof The result of the keyword.
2	wchar_t This is an integer type of a wide-character constant size.
3	div_t This is div The structure returned by the function.
4	ldiv_t This is ldiv The structure returned by the function.

Library macros

Here are the macros defined in the header file stdlib.h:

Serial number	Macro & Description
1	NULL This macro is a value of an empty pointer.
2	EXIT_FAILURE This is the value to return when the EXIT function fails.
3	EXIT_SUCCESS This is the value to return when the exit function is successful.
4	RAND_MAX This macro is the maximum value returned by the RAND function.
5	MB_CUR_MAX This macro indicates the maximum number of characters in the multi-byte character set, cannot be greater than MB_LEN_MAX.

The library function

Here are the functions defined in the header file stdlib.h:

Serial number	Function & Description
1	double atof(const char str) Put parameters str* The polar string pointed to a floating point (type Double).
2	int atoi(const char str) Put parameters str* The pointer to the string is converted to an integer (type INT type).
3	long int atol(const char str) Put parameters str* The polar string pointed to the string is converted to a long integer (type Long INT).
4	double strtod(const char str, char endptr) Put parameters str* The polar string pointed to a floating point (type Double).
5	long int strtol(const char str, char endptr, int base) Put parameters str* The polar string pointed to the string is converted to a long integer (type Long INT).
6	unsigned long int strtoul(const char str, char endptr, int base) Put parameters str* The polar string pointed to a symbolic long integer (type UNSigned long int type).
7	void *calloc(size_t nitems, size_t size) Assign the required memory space and return a pointer to it.
8	void free(void ptr) Before released calloc、malloc* or realloc Allocated memory space.
9	void *malloc(size_t size) Assign the required memory space and return a pointer to it.
10	void realloc(void ptr, size_t size) Try to call before calling malloc or calloc The size of the memory pointer to the allocated PTR.
11	void abort(void) Terminate an exception program.
12	int atexit(void (func)(void)) When the program is terminated normally, call the specified function. func* 。
13	void exit(int status) Make the program normally terminate.
14	char getenv(const char name) Search for the environment string points to Name and return the relevant value to the string.
15	int system(const char *string) The command specified by the string is transmitted to the host environment to be executed by the command processor.
16	void bsearch(const void key, const void base, size_t nitems, size_t size, int (compar)(const void , const void )) Execute two points.
17	void qsort(void base, size_t nitems, size_t size, int (compar)(const void , const void)) Array sort.
18	int abs(int x) Returns the absolute value of X.
19	div_t div(int numer, int denom) The molecule is divided by a denominator.
20	long int labs(long int x) Returns the absolute value of X.
21	ldiv_t ldiv(long int numer, long int denom) The molecule is divided by a denominator.
22	int rand(void) Returns a range of 0 to 0 RAND_MAX The pseudo random number is between.
23	void srand(unsigned int seed) This function is planted by a function rand Random number generator used.
24	int mblen(const char str, size_t n) Return parameters str* The length of the multi-byte character pointed to.
25	size_t mbstowcs(schar_t pwcs, const char str, size_t n) Put parameters str The string of string pointed to the multi-byte character is converted to parameters. pwcs Array pointed to.
26	int mbtowc(whcar_t pwc, const char str, size_t n) Inspection parameters str The multi-byte character pointed to.
27	size_t wcstombs(char str, const wchar_t pwcs, size_t n) Array pwcs The encoding in the stored coding is converted to multi-byte characters and store them in a string. str middle.
28	int wctomb(char str, wchar_t wchar) Check corresponding to parameters wchar* The encoded multibyte character given.