A two-dimensional array of C + + Inverse-day grammar series

A company's pen test, its own analysis of the answer, and in the back of the two-dimensional array element representation form to summarize. Novice friends do not nag, patience to read and remember that you will be helpful. Veteran veterans are also welcome to comment.

int A[4][4] = {{1,2,3,4},{50,60,70,80},{900,1000,1100,1200},{13000,14000,15000,16000}};int (*P1) [4] = A;int (*P2) [4] = &a[0];int *p3 = &a[0][0];p rintf ("%d,%d,%d,%d\n", * (* (a+1)-1), * (* (P1+3)-2) +1,* (* (p2-1) +16) +2,* (P3+sizeof (P1 )-3);

64-bit environment, ask the running result of the above code.

Well, to parse, the first two-dimensional array name points to the first line of the two-dimensional array,

int (*P1) [4]=a, is a pointer to an array of four integers;

int *p3=&a[0][0], a two-dimensional array is referenced by a one-dimensional array;

First output: A+1 is the address of the second row, * (a+1) is the address of the first element of the second row, minus one is the address of the element in front of it, that is, the fourth element in the first row, and the result is 4.

The second output: P1 and P2 and A are the same, p1+3 is the address of line fourth, * (P1+3) The address of the first element of line fourth, minus two is the address of the third element of the third row, and the result is 1101.

The third output: P2-1 is the fourth line address, * (p2-1) represents the first element of the fourth line address, plus 16 is a circle or this element, the result is 13002.

Fourth output: 64-bit environment, then sizeof (p1) is 8,p3+5 represents the fifth element of a one-dimensional array, the second element of the second row of a two-dimensional array, and the result is 60.

Well, let's make a summary:

The two-dimensional array element A[i][j] has the following types of references:

* (a[i]+j) //a[i] The address of the group I, plus J, which is the array I row J column address

* (* (a+i) +j) //a+i Address of Group I, * (a+i) to row 0 of array I, plus J for Row J of Line I address

A two-dimensional array of C + + Inverse-day grammar series