C-用malloc分配的內存過多

Question

我正在為一個學校項目工作，我必須創建二進制樹並將其放入動態數組中。 我指定我正在使用GCC（GNU編譯器）在Windows上工作。

typedef struct s_node * TN;
struct s_node {
    char * chain; //Name of the tree
    int occ; //Number of occurences
    int ht; //Tree's height
};
typedef struct s_binary_tree * TBA;
struct s_binary_tree {
    TN root;
    TBA stl; //Sub Tree Left
    TBA str; //Sub Tree Right
};

首先，我使用malloc（）分配內存以創建具有x平方的二叉樹的數組，然后為二叉樹分配內存。

TBA create_Binary_Tree(char * chain, int occ, int number_letters) {
    TBA tree = malloc(sizeof(TBA));
    tree->root = malloc(sizeof(TN));
    tree->root->chain = malloc(sizeof(char) * (number_letters + 1)); //+1 for the '\0'

    *(tree->root->chain) = '\0';
    strcpy(tree->root->chain,chain);
    tree->root->occ = occ;
    tree->root->ht = 1;

    tree->stl = NULL;
    tree->slr = NULL;

    return tree;
}

TBA * create_Array_Binary_Tree(char * fileName) {
    FILE * file;
    file = fopen(fileName,"r");
    if(!file) {
        exit(EXIT_FAILURE);
    }

    int number_letters;
    fscanf(file,"%d",&number_letters); //number_letters is the number of square that I want to allocate
    TBA * arr = malloc(sizeof(TBA) * number_letters);
    char * letter = malloc(sizeof(char) * 256);
    int occ, i;


    for(i = 0; i < number_letters; i++) { //number_letters = 1 in our example
        fscanf(file,"%s %d",letter,&occ);
        *arr = create_Binary_Tree(letter,occ,number_letters);
    printf("--Adr = %p--\n"arr); //Print the adress
        arr++;
    }
    arr -= i; //Reset the arr pointer

    fclose(file);

    return arr;
}

我的問題是，當我計算數組的大小時，程序告訴我數組大小x + 38平方。

int size_Array_Binary_Tree(TBA * arr) {
    int sz_arr = 0;

    while(*arr != NULL) {
printf("-T = %d\tAdr = %p-\n",sz_arr,arr); //Print the adress
    sz_arr++;
    arr++;
}

return sz_arr;
}

終奌站 ：

--Adr = 0000000000951430-- //1 square allocated
-T = 0  Adr = 0000000000951430- //The square allocated
-T = 1  Adr = 0000000000951438- //?
-T = 2  Adr = 0000000000951440- //?
-T = 3  Adr = 0000000000951448- //...
-T = 4  Adr = 0000000000951450-
-T = 5  Adr = 0000000000951458-
-T = 6  Adr = 0000000000951460-
-T = 7  Adr = 0000000000951468-
-T = 8  Adr = 0000000000951470-
-T = 9  Adr = 0000000000951478-
-T = 10 Adr = 0000000000951480-
-T = 11 Adr = 0000000000951488-
-T = 12 Adr = 0000000000951490-
-T = 13 Adr = 0000000000951498-
-T = 14 Adr = 00000000009514A0-
-T = 15 Adr = 00000000009514A8-
-T = 16 Adr = 00000000009514B0-
-T = 17 Adr = 00000000009514B8-
-T = 18 Adr = 00000000009514C0-
-T = 19 Adr = 00000000009514C8-
-T = 20 Adr = 00000000009514D0-
-T = 21 Adr = 00000000009514D8-
-T = 22 Adr = 00000000009514E0-
-T = 23 Adr = 00000000009514E8-
-T = 24 Adr = 00000000009514F0-
-T = 25 Adr = 00000000009514F8-
-T = 26 Adr = 0000000000951500-
-T = 27 Adr = 0000000000951508-
-T = 28 Adr = 0000000000951510-
-T = 29 Adr = 0000000000951518-
-T = 30 Adr = 0000000000951520-
-T = 31 Adr = 0000000000951528-
-T = 32 Adr = 0000000000951530-
-T = 33 Adr = 0000000000951538-
-T = 34 Adr = 0000000000951540-
-T = 35 Adr = 0000000000951548-
-T = 36 Adr = 0000000000951550-
-T = 37 Adr = 0000000000951558-
-T = 38 Adr = 0000000000951560- //?

返回的大小應為1，但返回39。請您能幫幫我嗎？

編輯：我從類型中刪除了指針，並適應了其余的但問題仍然存在。

typedef struct s_node TN;
struct s_node {
    ...
};

typedef struct s_binary_tree TBA;
struct s_binary_tree {
    TN * root;
    TBA * stl;
    TBA * str;
};

TBA * create_Binary_tree(...) {
    TBA * tree = malloc(sizeof(TBA));
    tree->root = malloc(sizeof(TN));
    ...
    return tree;
}

TBA ** create_Array_Binary_Tree(...) {
    ...
    TBA ** arr = malloc(sizeof(TBA *) * number_letters);
    ...
    for(i = 0; i < number_letters; i++) {
        ...
        arr[i] = malloc(sizeof(TBA));
        arr[i] = create_Binary_Tree(...);
        ...
    }
    ...
    return arr;
}

任何想法？

Answer 1

該程序有幾個錯誤：

TBA create_Binary_Tree(char * chain, int occ, int number_letters) {
    TBA tree = malloc(sizeof(TBA));
    ...
}

TBA是指向結構的指針 。 當您分配sizeof(TBA)您要求分配的內存量與指針所需的一樣，僅為4字節（32位）或8字節（64位）。 您想為結構分配空間：

TBA tree = malloc(sizeof(struct s_binary_tree));

同樣的問題在這里：

tree->root = malloc(sizeof(TN));

應該：

tree->root = malloc(sizeof(struct s_node));

只有TBA * arr = malloc(sizeof(TBA) * number_letters); 實際上是正確的。

避免使用strcpy 。

而不是像arr -= i;這樣的凌亂指針算法arr -= i; ，請使用第二個變量在其中存儲原始指針或您要修改的指針。

您不是終止arr NULL。 分配后，其中可能有垃圾。 如果您希望將其填充為哨兵，則最好確保將其填充為NULL：

memset(arr, 0, sizeof(TBA) * number_letters);
// Or use `calloc`, `bzero`, ...

這可能是您的size_Array_Binary_Tree給您奇怪結果的原因。