我在接受 C 中的 N 个字符串行时使用 fscanf 和 fgets 出现分段错误

Question

我有一个包含变量 x、y 和 z 的多项式结构

struct Node
{
    float coeff;
    int powX;
    int powY;
    int powZ;
    struct Node* next;
};

我想以powX powY powZ coeff的形式读取n用户输入的多项式，我有一个带有for循环的实现，但它给了我分段错误。 可能是什么问题呢？

void readPolynomial(struct Node** poly)
{
    struct Node* temp = (struct Node*)malloc(sizeof(struct Node));
    *poly = temp;

    int terms;
    fscanf(stdin, "%d", &terms);
    getchar();

    char entry[200];
    char * splitter;
    for(int i = 0; i < terms; i++)
    {
        fgets(entry, 200, stdin);
        
        splitter = strtok(entry," ");
        temp->powX = atoi(splitter);
        splitter = strtok(NULL, " ");
        temp->powY = atoi(splitter);
        splitter = strtok(NULL, " ");
        temp->powZ = atoi(splitter);
        splitter = strtok(NULL, " ");
        temp->coeff = atof(splitter);
        temp->next = NULL;
        if(i != terms-1)
        {
            temp->next = (struct Node*)malloc(sizeof(struct Node));
            temp = temp->next;
            temp->next = NULL;
        }
    }
}

这是我的主要 function：

int main()
{
    struct Node* first = NULL;

    readPolynomial(&first);
    return 0;
}

对于多项式4x⁵y⁴z² ： 5 4 2 4

样本输入：

3
5 4 2 4
1 6 0 -7
1 0 1 9

FULL CODE FUNCTION：获取两个多项式之和，以规范顺序打印

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

struct Node
{
    float coeff;
    int powX;
    int powY;
    int powZ;
    struct Node* next;
};


void readPolynomial(struct Node** poly)
{
    struct Node* temp = (struct Node*)malloc(sizeof(struct Node));
    *poly = temp;

    int terms;
    fscanf(stdin, "%d", &terms);
    getchar();

    char entry[200];
    char *splitter;
    for(int i = 0; i < terms; i++)
    {
        fgets(entry, 200, stdin);
        splitter = strtok(entry," ");
        temp->powX = atoi(splitter);
        splitter = strtok(NULL, " ");
        temp->powY = atoi(splitter);
        splitter = strtok(NULL, " ");
        temp->powZ = atoi(splitter);
        splitter = strtok(NULL, " ");
        temp->coeff = atof(splitter);
        temp->next = NULL;
        if(i != terms-1)
        {
            temp->next = (struct Node*)malloc(sizeof(struct Node));
            temp = temp->next;
            temp->next = NULL;
        }
    }
}

int degree(struct Node *term) {
    return (term->powX*pow(10, 2)) + (term->powY*pow(10, 1)) + (term->powZ*pow(10, 0));
}

int termCount(struct Node* poly)
{
    int count = 0;
    while(poly != NULL)
    {
        count++;
        poly = poly->next;
    }
    return count;
}

void displayPolynomial(struct Node* poly)
{
    int c = termCount(poly);
    struct Node *temp1, *t, *temp2;
    int tempX, tempY, tempZ, tempCoeff;
    for(int i = c-2; i>= 0; i--)
    {
        temp1 = poly;
        temp2 = temp1->next;
        for(int j = 0; j <= i; j++)
        {
            if(degree(temp1) < degree(temp2))
            {
                tempX = temp1->powX;
                tempY = temp1->powY;
                tempZ = temp1->powZ;
                tempCoeff = temp1->coeff;

                temp1->powX = temp2->powX;
                temp1->powY = temp2->powY;
                temp1->powZ = temp2->powZ;
                temp1->coeff = temp2->coeff;

                temp2->powX = tempX;
                temp2->powY = tempY;
                temp2->powZ = tempZ;
                temp2->coeff = tempCoeff;
            }
            temp1 = temp2;
            temp2 = temp2->next;
        }
    }
    t = poly;
    while(t != NULL)
    {
        printf("%d %d %d %.3f\n", t->powX, t->powY, t->powZ, t->coeff);
        t = t->next;
    }
}

void addPolynomials(struct Node** result, struct Node* first, struct Node* second)
{
    struct Node* temp = (struct Node*)malloc(sizeof(struct Node));
    temp->next = NULL;
    *result = temp;
    while(first && second)
    {
        if(((first->powX*pow(10, 2)) + (first->powY*pow(10, 1)) + (first->powZ*pow(10, 0))) < (((second->powX*pow(10, 2)) + (second->powY*pow(10, 1)) + (second->powZ*pow(10, 0)))))
        {
            temp->coeff = second->coeff;
            temp->powX = second->powX;
            temp->powY = second->powY;
            temp->powZ = second->powZ;
            second = second->next;

        }
        else if(((first->powX*pow(10, 2)) + (first->powY*pow(10, 1)) + (first->powZ*pow(10, 0))) > (((second->powX*pow(10, 2)) + (second->powY*pow(10, 1)) + (second->powZ*pow(10, 0)))))
        {
            temp->coeff = first->coeff;
            temp->powX = first->powX;
            temp->powY = first->powY;
            temp->powZ = first->powZ;
            first = first->next;
        }
        else
        {
            temp->coeff = first->coeff + second->coeff;
            temp->powX = first->powX;
            temp->powY = first->powY;
            temp->powZ = first->powZ;
            first = first->next;
            second = second->next;
        }
        if(first && second)
        {
            temp->next = (struct Node*)malloc(sizeof(struct Node));
            temp = temp->next;
            temp->next = NULL;
        }
    }
    while(first || second)
    {
        temp->next = (struct Node*)malloc(sizeof(struct Node));
        temp = temp->next;
        temp->next = NULL;

        if(second)
        {
            temp->coeff = second->coeff;
            temp->powX = second->powX;
            temp->powY = second->powY;
            temp->powZ = second->powZ;
            second = second->next;
        }

        else if(first)
        {
            temp->coeff = first->coeff;
            temp->powX = first->powX;
            temp->powY = first->powY;
            temp->powZ = first->powZ;
            first = first->next;
        }
    }
}

int main()
{
    struct Node* first = NULL;
    struct Node* second = NULL;
    struct Node* result = NULL;

    readPolynomial(&first);
    readPolynomial(&second);
    addPolynomials(&result, first, second);
    displayPolynomial(result);
    return 0;
}

样本输入：

3
1 6 0 -7
0 7 0 -6
7 0 0 1
5
1 0 1 9
0 7 0 -2
5 3 2 4
1 2 3 4
1 3 0 3

样品 Output：

7 0 0 1.000
5 3 2 4.000
1 6 0 -7.000
1 3 0 3.000
1 2 3 4.000
1 0 1 9.000
0 7 0 -8.000

Answer 1

编译时出现完整警告（在 gcc 中将是-Wall -Wextra ）。

在这种情况下，您会看到您不包括<string.h> ， C 允许隐式声明（ int (*)() ），但行为不是您想要的。

将以下内容添加到您的代码中，

#include <string.h>