44深入了解C指針之---指針安全

深入了解C指針之---指針安全

1   1 #include <stdio.h>
 2   2 
 3   3 int main(int argc, char **argv)
 4   4 {
 5   5     int var1;
 6   6     printf("input the var1: ");
 7   7     scanf("%d", &var1);
 8   8     int var2;
 9   9     printf("input the var2: ");
10  10     scanf("%d", &var2);
11  11 
12  12     printf("示範不恰當的指針聲明：\n");
13  13     int *ptr1, ptr2;
14  14     ptr1 = &var1;
15  15     ptr2 = var2;
16  16     printf("*ptr1: %d and ptr1: %p\n", *ptr1, ptr1);
17  17     printf("var1: %d and &var1: %p\n", var1, &var1);
18  18     printf("ptr2: %d and &ptr2: %p\n", ptr2, &ptr2);
19  19     printf("var2: %d and &var2: %p\n", var2, &var2);                                                                                                                                       
20  20     printf("\n");
21  21 
22  22 #define PINT int*
23  23     printf("使用宏定義的方式定義指針：\n");
24  24     PINT ptr3, ptr4;
25  25     ptr3 = &var1;
26  26     ptr4 = var2;
27  27     printf("*ptr3: %d and ptr3: %p\n", *ptr3, ptr3);
28  28     printf("var1: %d and &var1: %p\n", var1, &var1);
29  29     printf("ptr4: %d and &ptr4: %p\n", ptr4, &ptr4);
30  30     printf("var2: %d and &var2: %p\n", var2, &var2);
31  31     printf("\n");
32  32 
33  33     printf("使用類型定義的方式定義指針：\n");
34  34     typedef int* PPINT;
35  35     PPINT ptr5, ptr6;
36  36     ptr5 = &var1;
37  37     ptr6 = &var2;
38  38     printf("*ptr5: %d and ptr5: %p\n", *ptr5, ptr5);
39  39     printf("var1: %d and &var1: %p\n", var1, &var1);
40  40     printf("*ptr6: %d and ptr6: %p\n", *ptr6, ptr6);
41  41     printf("var2: %d and &var2: %p\n", var2, &var2);
42  42 
43  43     return 0;
44  44 }      

人就像是被蒙着眼推磨的驢子，生活就像一條鞭子；當鞭子抽到你背上時，你就隻能一直往前走，雖然連你也不知道要走到什麼時候為止，便一直這麼堅持着。