如何避免链表的分段错误

Question

我想编写一个使用链表的代码，从终端获取输入，然后打印出 table。

在这个例子中，我从元素 table 上传一些信息。

我遇到分段错误。

有人可以帮我理解为什么吗？

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

typedef struct element{
    char name[20];
    char symbol[20];
    float atom_weight;
    struct Element* next;
} element;


/* Add a new node to the top of a list */
element* insert_top(char name[20], char symbol[20], float atom_weight, element* head) {
    element *new_element;
    new_element = (element *) malloc(sizeof(element));
    new_element->name[20] = name;
    new_element->symbol[20] = symbol;
    new_element->atom_weight = atom_weight;

    new_element->next= head;
    head = new_element;
    printf("Top inserted");
    return head;
}

element* table=NULL;
int main()
{
    int choice=1, i=0;
    char name[256];
    char symbol[256];
    float atom_weight;

    printf("%d", choice);
    while (choice!=0){

        printf("\n Please enter element name:");
        scanf("%s", name);

        printf("\n Please enter element symbol:");
        scanf("%s", symbol);

        printf("\n Please enter atomic weight:");
        scanf("%f", &atom_weight);


        //printf("%s, %s,...Weight %f",name, symbol, atom_weight);
        insert_top(name, symbol, atom_weight, table);

        i=i+1;
        printf("\nDo you want to continue (Y=1/N=0)? ");
        scanf("%d", &choice); //You should add the space before %c, not after

    }
    printf("Out of cycle\n");
    printf("Size of table %lu\n", sizeof(table));

    printf("Weight %f",table->atom_weight);


    while (table->next != NULL){
        printf("\nElement: %s \t\t Symbol: %s  \t\t Atomic weight: %f\n",table[i].name, table[i].symbol,table[i].atom_>
        //printf("ciao");
        table=table->next;
    }
}

Answer 1

您需要使用 strcpy 复制字符串，请参阅 insert_top Element没有定义，应该是element。次要不转换 malloc 结果。

还有一些问题，char大小限制，scanf return代码有待检查。

你需要在最后释放 malloc 内存。

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

typedef struct element{
    char name[20];
    char symbol[20];
    float atom_weight;
    struct element* next;
} element;


/* Add a new node to the top of a list */
element* insert_top(char name[20], char symbol[20], float atom_weight, element* head) {
    element *new_element = malloc(sizeof(element));
    strcpy(new_element->name, name);
    strcpy(new_element->symbol, symbol);
    new_element->atom_weight = atom_weight;

    new_element->next= head;
    printf("Top inserted");
    return new_element;
}

int main()
{
    element* table=NULL;
    int choice=1;

    printf("%d", choice);
    while (choice!=0){
        char name[256];
        char symbol[256];
        float atom_weight;

        printf("\n Please enter element name:");
        scanf("%s", name);

        printf("\n Please enter element symbol:");
        scanf("%s", symbol);

        printf("\n Please enter atomic weight:");
        scanf("%f", &atom_weight);


        //printf("%s, %s,...Weight %f",name, symbol, atom_weight);
        table = insert_top(name, symbol, atom_weight, table);

        printf("\nDo you want to continue (Y=1/N=0)? ");
        scanf("%d", &choice); //You should add the space before %c, not after

    }
    printf("Out of cycle\n");
    
    for (element *e = table; e; e = e->next) {
        printf("\nElement: %s \t\t Symbol: %s  \t\t Atomic weight: %f\n",
               e->name, e->symbol, e->atom_weight);
    }          
    return 0;  
}

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