troubleshooting Question

About vector container in the STL (C++)

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pascal_lalonde asked on
C++
11 Comments1 Solution357 ViewsLast Modified:
Hello experts,

  I am programming in C++. I have a question the vector container of the STL.
Have a look at the code below.

  Why is the size of the structure line 24 bytes? I know there are 4 bytes for the
field nbPoints but where precisely the 20 others go (their meaning)?

Here is a fragment of the code:

typedef struct point
{
      int x;
      int y;
      int z;
} point;

typedef struct line
{
      int nbPoints;
      vector<point> points;
} line;

line myLine;
int sizeLine = sizeof(line);// 24 bytes
int sizeMyLine = sizeof(myLine);// 24 bytes


Thank you!


typedef struct point
{
	int x;
	int y;
	int z;
} point;
 
typedef struct line
{
	int nbPoints;
	vector<point> points;
} line;
 
line myLine;
int sizeLine = sizeof(line);// 24 bytes
int sizeMyLine = sizeof(myLine);// 24 bytes
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