program:
#include
Typedef struct aa {int b; char A1; char A2; char A3; char A4; char A5; char A6; char A7; char A8; char A9; char A10; Double C; char D;};
/ ************************************************** ***********************************************************
I originally thought:
TypedEf struct aa {int b; 4 4 CHAR A1; 1 3 8 CHAR A2; 1 9 CHAR A3; 1 10 CHAR A4; 1 11 CHAR A5; 1 12 CHAR A6; 1 13 CHAR A7; 1 14 CHAR A8; 1 15 CHAR A9; 1 16 CHAR A10; 1 7 24 Double C; 8 32 Char D; 1 7 40};
But actually
in principle:
1. The variable in the structure is aligned.
2. Variable storage is in units of char, with the same type
Explanation:
A1 is char, b is int, and there is three air spaces behind A1.
However, A2, A3, A4 or the A1 is the same type, so it is still stored behind the A1
A5 ~ A10 total 6 char
But thereafter is a Double C, so supplement two spaces
Typedef struct aa {int b; 4 4 CHAR A1; 1 5 / * A1 To align, make three char, but thereafter, the variables are also char, and three char * / char A2; 1 6 char A3; 1 7 char A4; 1 8
Char A5; 1 9 CHAR A6; 1 10 Char A7; 1 11 Char A8; 1 12 CHAR A9; 1 13 CHAR A10; 1 2 16 / * Has already occupied 6 char, it is a Double, so supplement two char Air level * / double C; 8 24 char D; 1 7 32};
*********************************************************** *************************************************** /
INT main () {char DD = '/ 0'; AA AA; CHAR TT = '/ 0';
Char CC [100]; STRCPY (CC, "0123456789AbcDefghijklmnopqrStuvwxyz"); Memcpy (& AA, CC, SIZEOF (AA)); Printf ("SizeOf (AA) = [% D] / N", SIZEOF (AA));
Printf ("% S / N", (char *) & aa); Printf ("A1 =% C / N", AA.A1); Printf ("A2 =% C / N", AA.A2); Printf "A9 =% C / N", AA.A9); Printf ("A10 =% C / N", AA.A10); Printf ("D =% C / N", AA.D);
Return 0;}
Compile:
CC tt.cpp
result:
181: a.outsizeof (aa) = [32] 0123456789ABCDefghijklmnopQrstuva1 = 4A2 = 5A9 = CA10 = DD = O
