Why we use memset to fill the structure with value 0, in socket programming c?
struct sockaddr_in servaddr, cliaddr;
// Creating socket file descriptor
if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
memset(&cliaddr, 0, sizeof(cliaddr));
In my previous work on structs i didn't fill the structures with value 0, but here in socket we always reset, fill 0, the struct before using it. Why is it important to fill 0 the structure?
c sockets struct memset
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
add a comment |
struct sockaddr_in servaddr, cliaddr;
// Creating socket file descriptor
if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
memset(&cliaddr, 0, sizeof(cliaddr));
In my previous work on structs i didn't fill the structures with value 0, but here in socket we always reset, fill 0, the struct before using it. Why is it important to fill 0 the structure?
c sockets struct memset
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
add a comment |
struct sockaddr_in servaddr, cliaddr;
// Creating socket file descriptor
if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
memset(&cliaddr, 0, sizeof(cliaddr));
In my previous work on structs i didn't fill the structures with value 0, but here in socket we always reset, fill 0, the struct before using it. Why is it important to fill 0 the structure?
c sockets struct memset
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
struct sockaddr_in servaddr, cliaddr;
// Creating socket file descriptor
if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
memset(&cliaddr, 0, sizeof(cliaddr));
In my previous work on structs i didn't fill the structures with value 0, but here in socket we always reset, fill 0, the struct before using it. Why is it important to fill 0 the structure?
c sockets struct memset
c sockets struct memset
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
asked Dec 28 '18 at 5:49
Henok TesfayeHenok Tesfaye
457317
457317
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
Unless the variables are declared as static storage duration, they will have an arbitrary value upon creation. Hence, it's always a good idea to set them to a known value before using them.
For example, if your next step after socket() is a connect() or bind(), they will very much want a specific structure value for client or server respectively.
It's no different really to the function:
void xyzzy(void) {
int plugh;
printf("%dn", plugh);
}
inasmuch as it may print any value.
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
add a comment |
In continuation of @paxdiablo explanation -
You may define a const static instance of the struct with the initial values.
static const struct sockaddr_in EmptyStruct;
A struct initializer may be used to set desired initial values (could be all 0es as by memset)
Then every time you want to reset the struct you can by
servaddr = EmptyStruct;
cliaddr = EmptyStruct;
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Unless the variables are declared as static storage duration, they will have an arbitrary value upon creation. Hence, it's always a good idea to set them to a known value before using them.
For example, if your next step after socket() is a connect() or bind(), they will very much want a specific structure value for client or server respectively.
It's no different really to the function:
void xyzzy(void) {
int plugh;
printf("%dn", plugh);
}
inasmuch as it may print any value.
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
add a comment |
Unless the variables are declared as static storage duration, they will have an arbitrary value upon creation. Hence, it's always a good idea to set them to a known value before using them.
For example, if your next step after socket() is a connect() or bind(), they will very much want a specific structure value for client or server respectively.
It's no different really to the function:
void xyzzy(void) {
int plugh;
printf("%dn", plugh);
}
inasmuch as it may print any value.
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
add a comment |
Unless the variables are declared as static storage duration, they will have an arbitrary value upon creation. Hence, it's always a good idea to set them to a known value before using them.
For example, if your next step after socket() is a connect() or bind(), they will very much want a specific structure value for client or server respectively.
It's no different really to the function:
void xyzzy(void) {
int plugh;
printf("%dn", plugh);
}
inasmuch as it may print any value.
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
Unless the variables are declared as static storage duration, they will have an arbitrary value upon creation. Hence, it's always a good idea to set them to a known value before using them.
For example, if your next step after socket() is a connect() or bind(), they will very much want a specific structure value for client or server respectively.
It's no different really to the function:
void xyzzy(void) {
int plugh;
printf("%dn", plugh);
}
inasmuch as it may print any value.
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
answered Dec 28 '18 at 5:54
paxdiablopaxdiablo
629k16912431664
629k16912431664
add a comment |
add a comment |
In continuation of @paxdiablo explanation -
You may define a const static instance of the struct with the initial values.
static const struct sockaddr_in EmptyStruct;
A struct initializer may be used to set desired initial values (could be all 0es as by memset)
Then every time you want to reset the struct you can by
servaddr = EmptyStruct;
cliaddr = EmptyStruct;
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
add a comment |
In continuation of @paxdiablo explanation -
You may define a const static instance of the struct with the initial values.
static const struct sockaddr_in EmptyStruct;
A struct initializer may be used to set desired initial values (could be all 0es as by memset)
Then every time you want to reset the struct you can by
servaddr = EmptyStruct;
cliaddr = EmptyStruct;
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
add a comment |
In continuation of @paxdiablo explanation -
You may define a const static instance of the struct with the initial values.
static const struct sockaddr_in EmptyStruct;
A struct initializer may be used to set desired initial values (could be all 0es as by memset)
Then every time you want to reset the struct you can by
servaddr = EmptyStruct;
cliaddr = EmptyStruct;
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
In continuation of @paxdiablo explanation -
You may define a const static instance of the struct with the initial values.
static const struct sockaddr_in EmptyStruct;
A struct initializer may be used to set desired initial values (could be all 0es as by memset)
Then every time you want to reset the struct you can by
servaddr = EmptyStruct;
cliaddr = EmptyStruct;
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
answered Dec 28 '18 at 6:02
RizwanRizwan
1,592419
1,592419
add a comment |
add a comment |
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