06-04-2009
You should not be using sizeof to determine string lengths. Use strlen for that. Your sizeof is returning the correct size (4 or 8 depending on your system's architecture).
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1. Programming
we know that sizeof never returns zero when used with structure
then why in this case it is returning zero
struct foo
{
char c;
};
void main()
{
struct foo f;
cout<<sizeof(f);
}
i am working on solaris 5.8
isn't the above function should return the size of empty structure (7 Replies)
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2. Programming
Hi,
char *s="yamaha";
cout<<s<<endl;
int *p;
int i=10;
p=&i;
cout<<p<<endl;
1) For the 1st "cout" we will get "yamaha" as output. That is we are getting "content of the address" for cout<<s.
2) But for integer "cout<<p" we are getting the "address only".
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3. Programming
Hello,
I'm trying to write a method which will return the extension of a file given the file's name, e.g. test.txt should return txt. I'm using C so am limited to char pointers and arrays. Here is the code as I have it:
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{
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4. Programming
If one wants to get a start address of a array or a string or a block of memory via a function, there are at least two methods to achieve it:
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5. Programming
Hi All,
is it possible to find out the size of an array of structures ( without using 'sizeof' operator). The condition is we have the array of structure instant but we are not aware of the elements inside the structure.
Can someone help me out?
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6. Programming
Hi,
There are some bewildering sizeof() questions I have in my mind. Could anyone shed some light on this?
int main() {
printf("%d\n", sizeof(main)); // Ans: 1
}
That is, the sizeof() a function identifier though it is treated internally as a pointer gives 1 byte always, why?
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7. Programming
Hi,
I have defined the class and call the sizeof(object to class) to get the size.
# include <iostream>
# include <iomanip>
using namespace std;
class sample
{
private:
int i;
float j;
char k;
public:
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{
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8. Programming
i have an array like
#define NUM 8
....
new_socket_fd = accept(socket_fd, (struct sockaddr *) &cli_addr, &client_length);
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9. Programming
Ignoring other considerations for a moment and in general ...
Would there be a difference in result (dot oh or execution) of:
A.
strncpy( a, b, sizeof(a) );
vs.
B.
c = sizeof(a);
strncpy( a, b, c );
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10. Programming
I am passing a char* to the function "reverse" and when I execute it with gdb I get:
Program received signal SIGSEGV, Segmentation fault.
0x000000000040083b in reverse (s=0x400b2b "hello") at pointersExample.c:72
72 *q = *p;
Attached is the source code.
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LEARN ABOUT LINUX
strlcpy
STRLCPY(3) BSD Library Functions Manual STRLCPY(3)
NAME
strlcpy, strlcat -- size-bounded string copying and concatenation
LIBRARY
Utility functions from BSD systems (libbsd, -lbsd)
SYNOPSIS
#include <bsd/string.h>
size_t
strlcpy(char *dst, const char *src, size_t size);
size_t
strlcat(char *dst, const char *src, size_t size);
DESCRIPTION
The strlcpy() and strlcat() functions copy and concatenate strings respectively. They are designed to be safer, more consistent, and less
error prone replacements for strncpy(3) and strncat(3). Unlike those functions, strlcpy() and strlcat() take the full size of the buffer
(not just the length) and guarantee to NUL-terminate the result (as long as size is larger than 0 or, in the case of strlcat(), as long as
there is at least one byte free in dst). Note that a byte for the NUL should be included in size. Also note that strlcpy() and strlcat()
only operate on true ``C'' strings. This means that for strlcpy() src must be NUL-terminated and for strlcat() both src and dst must be NUL-
terminated.
The strlcpy() function copies up to size - 1 characters from the NUL-terminated string src to dst, NUL-terminating the result.
The strlcat() function appends the NUL-terminated string src to the end of dst. It will append at most size - strlen(dst) - 1 bytes, NUL-
terminating the result.
RETURN VALUES
The strlcpy() and strlcat() functions return the total length of the string they tried to create. For strlcpy() that means the length of
src. For strlcat() that means the initial length of dst plus the length of src. While this may seem somewhat confusing, it was done to make
truncation detection simple.
Note, however, that if strlcat() traverses size characters without finding a NUL, the length of the string is considered to be size and the
destination string will not be NUL-terminated (since there was no space for the NUL). This keeps strlcat() from running off the end of a
string. In practice this should not happen (as it means that either size is incorrect or that dst is not a proper ``C'' string). The check
exists to prevent potential security problems in incorrect code.
EXAMPLES
The following code fragment illustrates the simple case:
char *s, *p, buf[BUFSIZ];
...
(void)strlcpy(buf, s, sizeof(buf));
(void)strlcat(buf, p, sizeof(buf));
To detect truncation, perhaps while building a pathname, something like the following might be used:
char *dir, *file, pname[MAXPATHLEN];
...
if (strlcpy(pname, dir, sizeof(pname)) >= sizeof(pname))
goto toolong;
if (strlcat(pname, file, sizeof(pname)) >= sizeof(pname))
goto toolong;
Since it is known how many characters were copied the first time, things can be sped up a bit by using a copy instead of an append:
char *dir, *file, pname[MAXPATHLEN];
size_t n;
...
n = strlcpy(pname, dir, sizeof(pname));
if (n >= sizeof(pname))
goto toolong;
if (strlcpy(pname + n, file, sizeof(pname) - n) >= sizeof(pname) - n)
goto toolong;
However, one may question the validity of such optimizations, as they defeat the whole purpose of strlcpy() and strlcat(). As a matter of
fact, the first version of this manual page got it wrong.
SEE ALSO
snprintf(3), strncat(3), strncpy(3)
HISTORY
The strlcpy() and strlcat() functions first appeared in OpenBSD 2.4, and made their appearance in FreeBSD 3.3.
BSD
May 31, 2007 BSD