C语言 尝试使用 malloc 为自定义结构分配内存时出错

Question

我正在尝试为我的c程序中的自定义堆栈分配一些动态内存。但是，我收到错误0xC0000005：在 malloc 调用期间访问冲突写入位置0x00000014。

这是我的结构定义和调用malloc的函数：

#include <stdio.h>
#include <stdlib.h>
#define EMPTY -1;
typedef enum boolean_tag { TRUE, FALSE } Boolean;
typedef enum direction_tag { ACROSS, DOWN } AnswerDirection;    /*The direction of an answer in the crossword*/
typedef struct answer_tag {
    /*A single 'Answer' is a single node making up a linked list*/
    int answerNumber;
    AnswerDirection direction;
    char *answerString;         /*The answer's value in chars*/
    struct answer_tag *nextAnswer;      /*Points to the next answer in the linked list*/
} Answer;
typedef struct space_tag {
    /*A single space inside of a board*/
    int numberOfCurrentAnswers; /*How many Answers currently cross through the space*/
    char value;
    int x;
    int y;
    struct space_tag *behindSpace;
    struct space_tag *nextSpace;
} Space;
    void InitAnswers(Answer *);
    Space *InitCrossword();
    Space *InitSpace();
    void ProgramClosingCleaning(Space *);
main(){
Space *board;
board = InitCrossword();
ProgramClosingCleaning(board);
}
void InitAnswers(Answer *answerKey){
}
Space *InitCrossword(){
int xLimit, yLimit;         /*Limits set*/
int xTraverse, yTraverse;   /*Coordinate variables to use in traversing*/
Space *currentSpace = NULL;
Space *nextSpace;           
printf("Please enter the size of the board: x yn");
scanf("%d %d", &xLimit, &yLimit);
for (xTraverse = 0; xTraverse < xLimit; xTraverse++){
    for (yTraverse = 0; yTraverse < yLimit; yTraverse++){
        nextSpace = InitSpace();
        nextSpace->x = xTraverse;
        nextSpace->y = yTraverse;
        nextSpace->numberOfCurrentAnswers = 0;
        nextSpace->value = EMPTY;
        nextSpace->behindSpace = currentSpace;
        currentSpace->nextSpace = nextSpace;
        currentSpace = nextSpace;
    }
}
while (currentSpace->behindSpace != NULL)
    currentSpace = currentSpace->behindSpace;
return currentSpace;
}
Space *InitSpace(){
return (Space *) malloc(sizeof(Space));
}
void ProgramClosingCleaning(Space *currentSpace){
Space *nextSpace;
while (currentSpace != NULL){
    nextSpace = currentSpace->nextSpace;
    free(currentSpace);
    }
}

感谢您的任何帮助！

Answer 1

我看到发布的代码有两个问题（编译器应该发出警告）：

• 隐式声明Init()和InitSpace()，这意味着它们的返回类型为 int
• Init()不返回值。

---

问题是InitCrossword()函数中的这一行：

currentSpace->nextSpace = nextSpace;

在 for 循环的第一次迭代中，currentSpace为 NULL。

Answer 2

我很确定您使用的语法会创建类型为 space_tag 的结构，而Space实际上是一个变量（请参阅 http://www.cplusplus.com/doc/tutorial/structures/）。

试试这个代码：

#include <stdio.h>
#include <stdlib.h>
typedef struct Space {
    int numberOfCurrentAnswers;
    char value;
    int x;
    int y;
    struct Space *lastSpace;
    struct Space *nextSpace;
};
main(){
    struct Space *space;
    space = Init();
}
Space *Init(){
    struct Space *nextSpace;
    nextSpace = InitSpace();
}
Space *InitSpace(){
    return (Space *) malloc(sizeof(Space));
}

根据发布的示例代码进行编辑

Answer 3

您缺少 Init(); 中的返回函数