46 lines
1.3 KiB
C
46 lines
1.3 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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int *input_score(int size)
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{
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int *arr = (int *)malloc(sizeof(int) * size);
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memset(arr, 0, sizeof(int) * 5); // 将 scores 指向的内存清零0
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for (int i = 0; i < size; i++)
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{
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printf("请输入第 %d 个学生的成绩: ", i + 1);
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scanf("%d", arr + i);
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}
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return arr;
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}
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int main()
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{
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int *scores = input_score(5);
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// scores = NULL 的判断是必须的，因为 malloc 分配内存失败时，会返回 NULL
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if (scores == NULL)
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{
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printf("内存分配失败\n");
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return 1;
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}
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for (int i = 0; i < 5; i++)
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{
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printf("%d ", *(scores + i));
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}
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printf("\n");
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printf("R%p\n", scores);
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free(scores); // 释放后，打印的前两个值是随机的，因为内存已经被释放了，但是后面的值还在，所以还能打印出来
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// free(scores); // 重复释放内存，会报错；一个指针只能释放一次内存
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printf("R%p\n", scores);
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for (int i = 0; i < 10000000; i++)
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;
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for (int i = 0; i < 5; i++)
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{
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// 会报错，因为 scores 指向的内存已经被释放了
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// free(scores + i); // 释放指针数组中的每一个元素 malloc 分配的内存
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printf("%d ", *(scores + i));
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}
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printf("\n");
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return 0;
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}
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