C-language array pointers (pointers to arrays)

Note: The definition of an array pointer differs from the array of pointers

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Pointer variable pointing to multidimensional array element

① pointer variable pointing to an array element
Example 6.7 outputs the values of the elements of the two-dimensional array. The method used here is to point to each element with a pointer variable with a base type of integer, outputting their values one by one.

#include <iostream>using namespacestd;intMain () {inta[3][4]={1,3,5,7,9, One, -, the, -, +, +, at}; int*p;//p is a pointer variable with a base type of integral type     for(p=a[0];p <a[0]+ A;p + +) cout<<*p<<" "; cout<<Endl; return 0;}

The results of the operation are as follows:
1 3 5 7 9 11 13 15 17 19 21 23

A few notes about pointer variables that point to array elements:

• P is a pointer to the integer data, in the For statement to P A[0], can also be written as "p=&a[0][0]".
• The condition of the loop end is "p<a[0]+12", as long as the p<a[0]+12 is satisfied, the loop body is continued.
• Execute "cout<<*p;" Output p The value of the column element currently referred to, and then execute p++ so that P points to the next column element.

② pointer variable pointing to a one-dimensional array of M elements
You can define a pointer variable that does not point to an integer element, but instead to a one-dimensional array that contains m elements. At this point, if the pointer variable p first points to a[0] (that is, p=&a[0]), then p+1 is not pointing to a[0][1], but the increment to a[1],p is measured in the length of the one-dimensional array, as shown in Figure 6.17.

Figure 6.17

"Example 6.8" outputs a two-dimensional array of values for any column element of any row.

#include <iostream>using namespacestd;intMain () {inta[3][4]={1,3,5,7,9, One, -, the, -, +, +, at}; int(*p) [4],i,j; CIN>>i>>J; P=A; cout<<* (* (p+i) +j) <<Endl; return 0;}

The operating conditions are as follows:
2 3
23

Because the "p=a" is executed, p points to the a[0]. So p+2 is the starting address of the row with the ordinal 2 in the two-dimensional array A (since p is a pointer variable to a one-dimensional array, so p plus 1 points to the next one-dimensional array), as shown in Figure 6.18. * (p+2) +3 is a array of 2 rows 3 column element addresses. * (* (p+2) +3) is the value of a[2][3].

Figure 6.18

3) Use pointers to arrays as function parameters
A one-dimensional array name can be passed as a function parameter, and a multidimensional array name can also be passed as a function parameter.

Example 6.9 outputs the values of the elements of the two-dimensional array. The title is the same as example 6.7, but the topic uses a function to implement the output, using multidimensional array function parameters.

#include <iostream>using namespacestd;intMain () {voidOutputint(*p) [4]);//function Declaration    inta[3][4]={1,3,5,7,9, One, -, the, -, +, +, at};  Output (a); //multidimensional array masterpiece function parameters    return 0;}voidOutputint(*p) [4])//A parameter is a pointer variable that points to a one-dimensional array{    inti,j;  for(i=0;i<3; i++)         for(j=0;j<4; j + +) cout<<* (* (p+i) +j) <<" "; cout<<Endl;}

The operating conditions are as follows:
1 3 5 7 9 11 13 15 17 19 21 23

C-language array pointers (pointers to arrays)