Standard C Episode 10

 1 /*
 2  * malloc练习
 3  *
 4  * */
 5 
 6 #include <stdlib.h>
 7 #include <stdio.h>
 8 
 9 int main()
10 {
11     int *p_value = NULL;
12 
13     p_value = (int *) malloc (1 * sizeof(int));
14     if (p_value) {
15         printf(" p_value是0x%p\n",  p_value);
16         printf("*p_value是%d\n", *p_value);
17         free(p_value);
18         p_value = NULL;
19     }
20     }
21 
22     return 0;
23 }

 1 /*
 2  * calloc(), realloc()练习
 3  *
 4  * 不同于malloc,calloc会将把开辟的存储空间初始化为零
 5  *
 6  * */
 7 
 8 #include <stdlib.h>
 9 #include <stdio.h>
10 
11 int main()
12 {
13     int *p_value = (int * ) calloc(4, sizeof(int));
14                 //(int * )   malloc(4 * sizeof(int));
15     if (p_value) {
16         printf(" p_value是0x%p\n", p_value);
17         printf("*p_value是%d\n", *p_value);
18         void *pointer = NULL;
19         pointer = realloc(p_value, 6 * sizeof(int));
20             //realloc(p_value, 0);实际效果就等于语句free(p_value);
21             //p_value = NULL, realloc(p_value, 4*sizeof(int));实际效果就
22            //等于语句p_value = NULL, p_value = (int *)malloc(4*sizeof(int));
23         if (pointer) {
24             p_value = (int * )pointer;
25         }
26         printf(" p_value是0x%p\n", p_value);
27         printf("*p_value是%d\n", *p_value);
28         free(p_value);
29         p_value = NULL;
30     }
31 }

 1 /*
 2  * Input: 1234
 3  * Output: 4321
 4  * */
 5 
 6 #include <stdio.h>
 7 #include <stdlib.h>
 8 
 9 int main()
10 {
11     typedef enum {N, Y} en_retry;
12 
13     en_retry over = N;
14     int *p_integer = NULL;
15     int *p_integers[100] = {NULL};
16 
17     int counter = 0;
18     do {
19         p_integer = (int *) malloc(sizeof(int) * 1);
20         if (p_integer) {
21             printf("Input an Integer");
22             scanf("%d", p_integer);
23             p_integers[counter++] = p_integer;
24         }
25         printf("Another?[Y/N]");
26         printf("%d\n", over);
27         scanf("%d", &over);
28         printf("%d\n", over);
29     } while (over);
30 
31     for (--counter; counter >= 0; counter--) {
32         printf("%d\t", *p_integers[counter]);
33         free(p_integers[counter]);
34     }
35     printf("\n");
36 
37     return 0;
38 }