stdlib
| double atof(const char *str) Converts the string pointed to, by the argument str to a floating-point number (type double). |
| int atoi(const char *str) Converts the string pointed to, by the argument str to an integer (type int). |
| long int atol(const char *str) Converts the string pointed to, by the argument str to a long integer (type long int). |
| double strtod(const char *str, char **endptr) Converts the string pointed to, by the argument str to a floating-point number (type double). |
| long int strtol(const char *str, char **endptr, int base) Converts the string pointed to, by the argument str to a long integer (type long int). |
| unsigned long int strtoul(const char *str, char **endptr, int base) Converts the string pointed to, by the argument str to an unsigned long integer (type unsigned long int). |
| void *calloc(size_t nitems, size_t size) Allocates the requested memory and returns a pointer to it. |
| void free(void *ptr) Deallocates the memory previously allocated by a call to calloc, malloc, or realloc. |
| void *malloc(size_t size)Allocates the requested memory and returns a pointer to it. |
| void *realloc(void *ptr, size_t size) Attempts to resize the memory block pointed to by ptr that was previously allocated with a call to malloc or calloc. |
| void abort(void) Causes an abnormal program termination. |
| int atexit(void (*func)(void)) Causes the specified function func to be called when the program terminates normally. |
| void exit(int status) Causes the program to terminate normally. |
| char *getenv(const char *name) Searches for the environment string pointed to by name and returns the associated value to the string. |
| int system(const char *string) The command specified by string is passed to the host environment to be executed by the command processor. |
| void *bsearch(const void *key, const void *base, size_t nitems, size_t size, int (*compar)(const void *, const void *)) Performs a binary search. |
| void qsort(void *base, size_t nitems, size_t size, int (*compar)(const void *, const void*)) Sorts an array. |
| int abs(int x) Returns the absolute value of x. |
| div_t div(int numer, int denom) Divides numer (numerator) by denom (denominator). |
| long int labs(long int x) Returns the absolute value of x. |
| ldiv_t ldiv(long int numer, long int denom) Divides numer (numerator) by denom (denominator). |
| int rand(void) Returns a pseudo-random number in the range of 0 to RAND_MAX. |
| void srand(unsigned int seed) This function seeds the random number generator used by the function rand. |
| int mblen(const char *str, size_t n) Returns the length of a multibyte character pointed to by the argument str. |
| size_t mbstowcs(schar_t *pwcs, const char *str, size_t n) Converts the string of multibyte characters pointed to by the argument str to the array pointed to by pwcs. |
| int mbtowc(whcar_t *pwc, const char *str, size_t n) Examines the multibyte character pointed to by the argument str. |
| size_t wcstombs(char *str, const wchar_t *pwcs, size_t n) Converts the codes stored in the array pwcs to multibyte characters and stores them in the string str. |
| int wctomb(char *str, wchar_t wchar) Examines the code which corresponds to a multibyte character given by the argument wchar. |
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int main () {
int n=4;//number of elements
int *a;
a = (int*)calloc(n, sizeof(int));
char *str;
str = (char *) malloc(15);
strcpy(str, "tutorialspoint");
str = (char *) realloc(str, 25);
strcat(str, ".com");//append string
free(str);
free( a );
return(0);
}