I have defined struct like
typedef struct {
char *oidkey;
int showperf;
char oidrealvalue[BUFSIZE];
char *oidlimits;
} struct_oidpairs;
and I have array of struct
struct_oidpairs b[] ={{.....},....}
and I want to copy it to new struct array a[]
please help
Something like this:
memcpy(dest, src, sizeof(struct) * sizeof(src));
oidkey and oidlimits are constants and not subject to be changed in the copied version of the array AND both the source during the lifetime of the copied array
a[i]=b[i]; mentioned in the down voted answer (except for the b.size() part, of course)? If the array size is specified properly, wouldn't struct copying work similar to a shallow memcpy?Your struct contains pointers as data members, this means you will have to roll out your own copy function that will do something sensible with the pointers. memcpy only works is all the data related to the struct is stored in the struct.
For real copy of the contents, follow Sjoerd's answer and then:
for (i = 0; i < sizeof(src); i++)
{
if (src[i].oidkey != NULL)
{
dest[i].oidkey = malloc(strlen(src[i].oidkey) + 1);
strcpy(dest[i].oidkey, src[i].oidkey);
}
if (src[i].oidlimits != NULL)
{
dest[i].oidlimits = malloc(strlen(src[i].oidlimits) + 1);
strcpy(dest[i].oidlimits, src[i].oidlimits);
}
}
You may consider memcpy if you are interested in speed.
Update:
This solution will crash if
oidkeyoroidlimitsare!= NULLand not'\0'-terminated means not initialized
strdup is not a standard function. In other words, there's no such function as strdup in C.Makes NOT a deep copy:
struct_oidpairs b[] = {...};
size_t len = sizeof b/sizeof*b;
struct_oidpairs *a = malloc(sizeof b);
if( !a ) /* ERROR handling */
memcpy( a, b, sizeof b );
...
free( a );
or
while( len-- )
a[len] = b[len];
...
free( a );
maybe using :
for(int i=0; i<b.size() ;i++)
//I am not sure if this is the correct name for the size function
{
a[i]=b[i];
}
typedef struct { ... } struct_oidpairs? Why not juststruct oidpairs { ... }?