Question

来自外部编译器的新图片。退出代码可以吗？

这是完整的代码。在将所需的输出打印到屏幕后，我遇到了一个故障程序吹响的麻烦。我想这是我为结构数组分配内存的方式以及for循环中每个结构的.name字段的问题。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>

#define MAX_NAME_LEN 50

typedef struct stud
{
char *name;
int marks[4];
float avg;
}student;


student* Create_Class(int);
void Avg_Mark(student*);
void Print_One(student*);
void printExcellent(student*);

void main()
{
int size, i;
student *arr, *newArr;
printf("\nEnter the number of students: ");
scanf_s("%d", &size);
newArr = Create_Class(&size);
for (i = 0; i < size; i++)
{
    printExcellent(newArr+i);
}
for (i=0;i<size;i++) free(newArr[i].name);
free(newArr);
_getch();
}

student* Create_Class(int size)
{
student *p;
char str[MAX_NAME_LEN];
int i, j;
p = (student*)calloc(size , sizeof(student));
if (!p)
{
    printf("Memory allocation failure.");
    exit(1);
}

for (i = 0; i < size; i++)
{
    printf("Enter your name: ");
    rewind(stdin);
    gets(str);
    p[i].name = (char*)calloc(strlen(str)+1,sizeof(char));
    if (!(p[i].name))
    {
        printf("Memory allocation error!");
        exit(1);
    }
    strcpy_s(p[i].name,50,str);
    printf("Enter your marks: ");
    for (j = 0; j < 4; j++)
    {
        scanf_s("%d", &p[i].marks[j]);
    }
    Avg_Mark(p + i);
}
return p;
}


void Avg_Mark(student* s)
{
int i, sum=0;
for (i = 0; i < 4; i++)
    sum += s->marks[i];
s->avg = (float)sum / 4;
}


void Print_One(student* s)
{
printf("The average of %s is %.1f\n", s->name, s->avg);
}

void printExcellent(student* s)
{
if ((s->avg) > 85)
    Print_One(s);
}

Answer 1

要指出我为您看到的所有可疑物：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>

#define MAX_NAME_LEN 50

typedef struct stud
{
    char *name;
    int marks[4];
    float avg;
}student;


student* Create_Class(int);
void Avg_Mark(student*);
void Print_One(student*);
void printExcellent(student*);

void main()
{
    int size, i;
    student *arr, *newArr;
    printf("\nEnter the number of students: ");
    scanf_s("%d", &size);

    // This is wrong. Remove the &...
    newArr = Create_Class(&size);

    for (i = 0; i < size; i++)
    {
        printExcellent(newArr+i);
    }
    for (i=0;i<size;i++) free(newArr[i].name);
    free(newArr);
    _getch();
}

student* Create_Class(int size)
{
    student *p;
    char str[MAX_NAME_LEN];
    int i, j;

    // Consider checking size for a sane value.

    // Ok, allocate an array of students.
    p = (student*)calloc(size , sizeof(student));
    if (!p)
    {
        printf("Memory allocation failure.");
        exit(1);
    }

    for (i = 0; i < size; i++)
    {
        printf("Enter your name: ");

        // These 2 lines scare the heck out of me.  I'd really do this differently.
        // gets is the devil and the see:
        // https://stackoverflow.com/questions/20052657/reversing-stdin-in-c
        // for why this may not work well.

        rewind(stdin);
        gets(str);

        // What if str is not a terminated string?  Then 1 char of 0?  Guess this is ok.  Hope it doesn't overflow on the copy below though (consider fixed max size and not using a temporary)
        p[i].name = (char*)calloc(strlen(str)+1,sizeof(char));
        if (!(p[i].name))
        {
            printf("Memory allocation error!");
            exit(1);
        }
        // Do a fast copy of up to 50 chars. I'd really want to verify this output to be sure it works. 
        strcpy_s(p[i].name,50,str);
        printf("Enter your marks: ");
        for (j = 0; j < 4; j++)
        {
            // Hope this inputs the way you want.
            scanf_s("%d", &p[i].marks[j]);
        }

        // This should work, but I prefer more explicit pointers.
        Avg_Mark(p + i);
    }

    return p;
}


void Avg_Mark(student* s)
{
    // What if s is Null?

    int i, sum=0;

    // 4 is a magic number.  Make this a constant.
    for (i = 0; i < 4; i++)
        sum += s->marks[i];

    // This won't be as accurate as you want.  Consider an integer solution.
    s->avg = (float)sum / 4;
}


void Print_One(student* s)
{
    // What if s is Null?  What about s->name?
    printf("The average of %s is %.1f\n", s->name, s->avg);
}

void printExcellent(student* s)
{
    // What if s is Null?
    if ((s->avg) > 85)
        Print_One(s);
}

注意：在阅读这段代码时，除了大小上的＆和可能的get / rewind调用之外，我没有看到任何“红色标志”。我仍然会向您的函数添加null断言，并使用调试器进行遍历以确保一切都如您所愿。坦白说，这里发生的事情足以让我在编写注释时更喜欢调试器的帮助而不是快速跟踪代码。

更新

如果我将您所有的scanf_s更改为scanf()，请将您的gets() / rewind()调用替换为简单的scanf("%s", str)调用，并将时髦的strcpy_s()函数更改为一个更简单的strcpy()或strncpy()调用，您的程序似乎对我来说没有崩溃。我的钱是，strcpy_s()调用在进行“快速”复制时正在破坏RAM。

出现致命错误代码-损坏的堆

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