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Runtime-Support Functions - Summary
General Utilities
Header File:
stdlib _ h
Function and Syntax
Description
int
abs(j)
int
j;
Returns the absolute value of j
void
abort ( )
Terminates a program abnormally
void
atexit(fun)
Registers the function point to by fun. to be called without
void
(*fun) ();
arguments at normal program termination
double
atof(nptr)
Converts an ASCII string to a floating-point value
char *nptr;
int
atoi(nptr)
char
*nptr;
Converts an ASCII string to an integer value
long int atol(nptr)
c ar
*nptr;
Converts an ASCII string to a long integer
void
*bsearch(key, base, nme lb, size, compar)
void
*key, *base;
Searches through an array of nmemb objects for a member
size-t nmemb, size;
that matches the object that key points to
int
(*compar) () ;
void
*calloc(nmemb, size)
Allocates and clears memory for nmemb objects. each of
size-t
nmemb, size
size bytes
div-t
div(numer, denom)
Divides numer by denom
int
numer, denom
void
exit(status)
Terminates a program normally
int
status;
void
free(ptr)
Deallocates memory space allocated by malloc. calloc. or
void
*ptr;
realloc
long int
labs(j)
Returns the absolute value of j
long int
j;
Idiv_t
Idiv(numer, denom)
long int
numer, denom
Divides numer by denom
int
Itoa(n, buffer)
Converts n to the equivalent ASCII string
long
n;
char
*buffer;
void
*malloc(size)
Allocates memory for an object of size bytes
size-t
size;
void
minit()
Resets all the memory previously allocated by malloc, calloc,
or realloc
char
*movmem(src,dest,count)
char
*src, *dest;
int
count;
Moves count bytes from one address to another
70Id
qsort(base, nmemb, size
compar)
void
*base;
Sorts an array of nmemb members; base points to the first
size-t nmemb, size;
member of the unsorted array and size specifies the size
int
(*compar)();
of each member
int
rand()
Returns a sequence of pseudo-random integers in the range
o
to RAN D-MAX
void
*realloc(ptr,
size)
Changes the size of an allocated memory space
void
*I?tr-
size-t sl.ze;
void
srand(seed)
Uses seed to reset the random number generator so that
unsigned int
seed;
a subsequent call to rand produces a new sequence of pseu-
do-random numbers
double
strtod(n~tr,
endptr)
Converts an ASCII string to a floating-point value
char
*nptr, * endptr;
long int
strtol(nptr, end P tr
1
base)
char *nptr, **endptr;
Converts an ASCII string to a long integer
int
base;
unsigned long int
strtoul(np r, endptr, base)
char *nptr,
int
base;
**endptr;
Converts an ASCII string to an unsigned long integer
6-11
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