c - 学生平均数的链表程序

Question

我是 C 编程新手，尤其是链表。有人可以帮我修改我的代码吗？当我编译程序时没有错误，但当我尝试运行程序时，其输出是错误的。不知道是存储错误还是打印错误。

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

/* self-referential structure */
struct listNode {
    char name[80];
    char subject[80]; /* each listNode contains a character */
    float unit;
    float grade;
    struct listNode *nextPtr; /* pointer to next node */
}; /* end structure listNode */

typedef struct listNode ListNode; /* synonym for struct listNode */
typedef ListNode *ListNodePtr; /* synonym for ListNode* */

/* prototypes */
void insert(ListNodePtr *sPtr, char SUB[80], float grade, float unit, char NAME[80]);
int isEmpty(ListNodePtr sPtr);
void printList(ListNodePtr currentPtr, ListNodePtr *sPtr);
void instructions(void);

int main(void)
{
    ListNodePtr startPtr = NULL; /* initially there are no nodes */
    int choice; /* user's choice */
    float grades, units;
    char subn[80], stdn[80];
    int i, j, std = 0, sub = 0;

    instructions(); /* display the menu */
    printf("? ");
    scanf("%d", &choice);

    /* loop while user does not choose 3 */
    while (choice != 3) {
        switch (choice) {
        case 1: /* input data */
            printf("Number of Students: (at least 5 students)\n");
            scanf("%d", &std);

            for (i = 0; i < std; i++) {
                printf("\nStudent name: ");
                scanf("%s", &stdn);
                printf("How many subjects?\n");
                scanf("%d", &sub);
                for (j = 0; j < sub; j++) {
                    printf("\nSub­ject: ");
                    scanf("%s", &subn);
                    printf("Units­: ");
                    scanf("%f", &units);
                    printf("Final­ Grade: ");
                    scanf("%f", &grades);
                    insert(&startPtr, subn, grades, units, stdn);
                }
            }
            break;

        case 2:
            printList(startPtr, &startPtr);
            break;

        default:
            printf("Invalid choice.\n\n");
            instructions();
            break;
        } /* end switch */

        printf("\n\n? ");
        scanf("%d", &choice);
    } /* end while */

    printf("End of run.\n");
    return 0; /* indicates successful termination */
} /* end main */

/* display program instructions to user */
void instructions(void)
{
    printf("Enter your choice:\n"
        " 1 to Input Student Data.\n"
        " 2 to Display Student Data.\n"
        " 3 to end.\n");
} /* end function instructions */

/* for series */
void insert(ListNodePtr *sPtr, char SUB[80], float grade, float unit, char NAME[80])
{
    ListNodePtr newPtr; /* pointer to new node */
    ListNodePtr previousPtr; /* pointer to previous node in list */
    ListNodePtr currentPtr; /* pointer to current node in list */

    newPtr = malloc(sizeof(ListNode)); /* create node */

    if (newPtr != NULL) { /* is space available */
        strcpy(newPtr->na­me, NAME);
        strcpy(newPtr->subject, SUB); /* place value in node */
        newPtr->grade = grade;
        newPtr->unit = unit;
        newPtr->nextPtr = NULL; /* node does not link to another node */

        previousPtr = NULL;
        currentPtr = *sPtr;

        /* insert new node at beginning of list */
        if (previousPtr == NULL) {
            newPtr->nextPtr = *sPtr;
            *sPtr = newPtr;
        } /* end if */
        else { /* insert new node between previousPtr and currentPtr */
            previousPtr->nex­tPtr = newPtr;
            newPtr->nextPtr = currentPtr;
        } /* end else */
    } /* end if */
    else {
        printf("Student data not inserted. No memory available.\n");
    } /* end else */
} /* end function insert */

int isEmpty(ListNodePtr sPtr)
{
    return sPtr == NULL;
} /* end function isEmpty */

/* Print the list */
void printList(ListNodePtr currentPtr, ListNodePtr *sPtr)
{
    float total = 0.00, total2 = 0.00;
    /* if list is empty */
    if (currentPtr == NULL) {
        printf("List is empty.\n\n");
    } /* end if */
    else {
        printf("\n");
        printf("%-20s\t%s\­t%s\n", "Subject", "Units", "Final Grade");
        /* while not the end of the list */
        while (currentPtr != NULL) {
            printf("Student­ Name: %s\n", currentPtr->name);
            printf("%-20s\t%.2f\t%.2f\n­", currentPtr->subject, ­ currentPtr->unit, currentPtr->grade);
            total += currentPtr->unit;
            total2 += currentPtr->unit*cur­rentPtr->grade;
            currentPtr = currentPtr->nextPtr;
        } /* end while */

        printf("\nWeight:­ %.2f", total2 / total);
        printf("\n///////­/////////////////////­/////////////////////­///");
    } /* end else */
} /* end function printList */

Answer 1

标题

嗨，我没有仔细查看代码。但是，快速浏览后我发现了以下基本问题

nextPtr 应该是一个指针，您正在创建一个实例并复制下一个结构的内容。这效率不高。我将声明如下

struct listNode *nextPtr;/指向下一个节点的指针 */

我将再次更改以下typedef ListNode ListNodePtr;typedef ListNode ListNodePtr;

至typedef ListNode *ListNodePtr;

尝试用这个重构你的代码，看看效果如何。如果没有帮助，我晚上可以详细看看。