Hi Experts
I need some help in static memory allocation in C. I have a program in which I declared 2 variables, one char array and one integer. I was little surprised to see the addresses of the variables.
First:
Code:
int x;
char a[2];
printf("%u %u\n', &x, a);
I got the addresses displayed as : 3219437172 3219437170
The above result is straight forward wherein the array a got 2 bytes allocated.
Second:
When I changed the program as below:
Code:
int x;
char a[3];
printf("%u %u\n', &x, a);
I got the addresses displayed as : 3219437172 3219437144
The array a got allocated 28 bytes when the declaration is for 3 bytes.
Hello!
First of all, forgive me for bad English.
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#include <string.h>
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cpy(a1,a2);
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Discussion started by: Tyler_92
7 Replies
LEARN ABOUT OSX
posix_memalign
POSIX_MEMALIGN(3) BSD Library Functions Manual POSIX_MEMALIGN(3)NAME
posix_memalign -- aligned memory allocation
SYNOPSIS
#include <stdlib.h>
int
posix_memalign(void **memptr, size_t alignment, size_t size);
DESCRIPTION
The posix_memalign() function allocates size bytes of memory such that the allocation's base address is an exact multiple of alignment, and
returns the allocation in the value pointed to by memptr.
The requested alignment must be a power of 2 at least as large as sizeof(void *).
Memory that is allocated via posix_memalign() can be used as an argument in subsequent calls to realloc(3), reallocf(3), and free(3). (Note
however, that the allocation returned by realloc(3) or reallocf(3) is not guaranteed to preserve the original alignment).
NOTES
posix_memalign() should be used judiciously as the algorithm that realizes the alignment constraint can incur significant memory overhead.
RETURN VALUES
The posix_memalign() function returns the value 0 if successful; otherwise it returns an error value.
ERRORS
The posix_memalign() function will fail if:
[EINVAL] The alignment parameter is not a power of 2 at least as large as sizeof(void *).
[ENOMEM] Memory allocation error.
SEE ALSO free(3), malloc(3), realloc(3), reallocf(3), valloc(3), malloc_zone_memalign(3)STANDARDS
The posix_memalign() function conforms to IEEE Std 1003.1-2001 (``POSIX.1'').
BSD April 9, 2008 BSD