在这个程序中,我声明了一个结构和几个成员,并且我使用了一个包含两个元素的数组作为这个特定结构的实例。我在这个结构中使用了一个 5 元素数组。一个特殊的事情是,在主函数中,当我尝试获取 5 元素数组中不存在的第 6 个元素的地址时,我得到了下一个结构的第一个成员整数的地址。为什么当我尝试访问不存在的数组元素时没有显示错误,为什么两个成员具有相同的地址?
#include<stdio.h>
struct {int num1,num2; char s1; int *ptr; int abc[5]; }a[2];
void main(){
int start, last;
start = &a[1].num1;
last = &a[0].num1;
printf("\nSize of the Structure : %d Bytes", start-last);
printf("\naddress of num1 in structure a[0] is %d", &a[0].num1);
printf("\naddress of num2 in structure a[0] is %d", &a[0].num2);
printf("\naddress of char in structure a[0] is %d", &a[0].s1);
printf("\naddress of ptr in structure a[0] is %d", &a[0].ptr);
printf("\naddress of I element in array abc[5] in structure a[0] is %d", &a[0].abc[0]);
printf("\naddress of II element in array abc[5] in structure a[0] is %d", &a[0].abc[1]);
printf("\naddress of III element in array abc[5] in structure a[0] is %d", &a[0].abc[2]);
printf("\naddress of IV element in array abc[5] in structure a[0] is %d", &a[0].abc[3]);
printf("\naddress of V element in array abc[5] in structure a[0] is %d", &a[0].abc[4]);
**printf("\naddress of VI element in the 5 element array abc[5] in structure a[0] is %d", &a[0].abc[5]);
printf("\naddress of num1 in structure a[1] is %d", &a[1].num1);**
printf("\n");
}
kevin@kevin-desktop:~/Documents/programs$ gcc --version
gcc (Ubuntu 4.4.3-4ubuntu5.1) 4.4.3
Copyright (C) 2009 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
kevin@kevin-desktop:~/Documents/programs$ gcc structure_size.c -o structure_size
structure_size.c: In function ‘main’:
structure_size.c:15: warning: assignment makes integer from pointer without a cast
structure_size.c:17: warning: assignment makes integer from pointer without a cast
structure_size.c:21: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:23: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:25: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘char *’
structure_size.c:27: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int **’
structure_size.c:29: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:31: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:33: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:35: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:37: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:39: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
structure_size.c:41: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘int *’
kevin@kevin-desktop:~/Documents/programs$ ./structure_size
Size of the Structure : 36 Bytes
address of num1 in structure a[0] is 134520896
address of num2 in structure a[0] is 134520900
address of char in structure a[0] is 134520904
address of ptr in structure a[0] is 134520908
address of I element in array abc[5] in structure a[0] is 134520912
address of II element in array abc[5] in structure a[0] is 134520916
address of III element in array abc[5] in structure a[0] is 134520920
address of IV element in array abc[5] in structure a[0] is 134520924
address of V element in array abc[5] in structure a[0] is 134520928
**address of VI element in the 5 element array abc[5] in structure a[0] is 134520932
address of num1 in structure a[1] is 134520932**
kevin@kevin-desktop:~/Documents/programs$