如何在C中复制结构数组

Question

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

Answer 1

像这样：

memcpy(dest, src, sizeof(struct) * sizeof(src));

Answer 2

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.

Answer 3

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:

• Following harper 's code, I updated the code to check NULL pointers
• This is a quoted note from gordongekko :

  This solution will crash if oidkey or oidlimits are != NULL and not '\\0' -terminated means not initialized

Answer 4

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 );

Answer 5

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];
}