What is the best method (performance) to put an int
into a char
array? This is my current code:
data[0] = length & 0xff;
data[1] = (length >> 8) & 0xff;
data[2] = (length >> 16) & 0xff;
data[3] = (length >> 24) & 0xff;
data
is a char
array (shared ptr) and length
is the int
.
Are you looking for memcpy
char x[20];
int a;
memcpy(&a,x,sizeof(int));
Your solution is also good as it is endian safe .
On a side note:-
Although there is no such guarantee that sizeof(int)==4
for any particular implementation.
Just use reinterpret_cast
. Use the data array as if it were an int pointer.
char data[sizeof(int)];
*reinterpret_cast<int*>(data) = length;
BTW memcpy
is much slower than this, because it copies byte by byte using a loop.
In the case of an integer, this will just be a straightforward assignment.
This is the only way. Theoretically you could use memcpy
or reinterpret_cast
but you can't due to problems with endians .
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