• C/C++中的指针数组和数组指针


    1. 指针数组

      定义:int *p[n],由于[]的优先级高于*,p和[]结合成一个数组,该数组的元素存储的是int类型的指针,由于数组内容是指针,因此p+1的步长是sizeof(int*),在32位机器上,步长通常是4个字节;

      int a[3][4];

      int *p[3]; // 指针数组,具有3个类型为(int*)的元素;

      p[0] = a[0]; // 将第一个元素的值赋值为a[0];

      p[1] = a[1]; // 将第二个元素的值赋值为a[1];

      p[2] = a[2]; // 将第三个元素的值赋值为a

      

    2. 数组指针:

      定义:int (*p)[n],由于()的优先级高于[],p和()结合成一个指针,指向一个具有n个int类型元素的数组,由于指针指向的是一个数组,p+1的步长是sizeof(int)*n,因此数组指针又可以称为行指针,在2维数组中,其步长是一行元素的总长度;

      int a[3][4];

      int (*p)[4] = a; // 数组指针,指向一个具有4个元素的一维数组,现在p的指向的地址和a的首地址一样;

      p++; // 步长为sizeof(int) * 4,指向二维数组的下一行的地址,即&a[1];

    例子:

     1 int a[][3] = {
     2         { 11, 12, 13 },
     3         { 21, 22, 23 },
     4         { 31, 32, 33 }
     5     };
     6     int b[] = { 41, 42, 43, 44 };
     7     
     8     int (*pa)[3] = a;
     9     int (*pb)[4] = &b;
    10     int *pc = b;
    11     int *pd[3];
    12     pd[0] = a[0];
    13     pd[1] = a[1];
    14     pd[2] = b;
    15     int **pe = (int**)(new char[sizeof(int*) * 2]);
    16     pe[0] = a[0];
    17     pe[1] = a[1];
    18     *(pe + 2) = a[2];
    19     
    20

    打印:

     1   printf("pa %p %p 
    ", *pa, *(pa + 1));
     2     printf("pa %d %d %d 
    ", **pa, **(pa + 1), *(*(pa + 1) + 2));
     3     printf("pb %p %p 
    ", *pb, *(pb + 1));
     4     printf("pb %d %d 
    ", **pb, **(pb + 1));
     5     printf("pc %p %p 
    ", pc, pc + 1);
     6     printf("pc %d %d 
    ", *pc, *(pc + 1));
     7     printf("pd %p %p %p %p 
    ", pd[0], pd[1], *(pd + 2), *(pd + 2) + 1);
     8     printf("pd %d %d %d %d 
    ", *pd[0], *(pd[1] + 1), **(pd + 2), *(*(pd + 2) + 1));
     9     printf("pe %p %p %p 
    ", pe[0], pe[1], *(pe + 2));
    10     printf("pe %d %d %d 
    ", *pe[0], *(pe[1] + 1), *(*(pe + 2) + 1));
    11 
    12   pa 0x7fff5fbff7e0 0x7fff5fbff7ec 
    13   pa 11 21 23 
    14   pb 0x7fff5fbff7d0 0x7fff5fbff7e0 
    15   pb 41 11 
    16   pc 0x7fff5fbff7d0 0x7fff5fbff7d4 
    17   pc 41 42 
    18   pd 0x7fff5fbff7e0 0x7fff5fbff7ec 0x7fff5fbff7d0 0x7fff5fbff7d4 
    19   pd 11 22 41 42 
    20   pe 0x7fff5fbff7e0 0x7fff5fbff7ec 0x7fff5fbff7f8 
    21   pe 11 22 32 
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  • 原文地址:https://www.cnblogs.com/iRidescent-ZONE/p/5584026.html
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