爲什麼輸出字符串以奇怪的方式連接？

我想使用我的泛型向量來保存csv文件中某行的數據。但是我遇到了一個問題。我輸入的是：爲什麼輸出字符串以奇怪的方式連接？

MonsterID，名稱，生命值，攻擊，防禦，AttackTimes，黃金，指數，特別

輸出成爲

Field 0 would be MonsterIName 
Field 1 would be Name 
Field 2 would be HitpointAttack 
Field 3 would be Attack 
Field 4 would be Defence 
Field 5 would be AttackTiGold 
Field 6 would be Gold 
Field 7 would be Exp 
Field 8 would be Special

這裏是代碼的部分與此問題有關：

Vector類型的定義：

typedef void (*VectorFreeFunction)(void *element); 

typedef struct Vector { 
    void *elements; // An array of elements 
    int capacity;  // The allocated size of the array 
    int size;   // The number of elements in use 
    size_t elemSize; // Size of the data type of the element. 
    VectorFreeFunction freeFunc; 
} Vector;

csv.c

... 
Vector *getfields(char *line) { 
    int i = 0; 
    const char *token; 

    Vector *fields = vectorAlloc(sizeof(char*), NULL); 

    for (token = strtok(line, ","); 
     token && *token; 
     token = strtok(NULL, ",\n"), i++) 
    { 
     vectorPush(fields, (const void*)token); 
    } 

    for (int i = 0; i != fields->size; i++) { 
     printf("Field %d would be %s\n", i, (const char*)vectorAt(fields, i)); 
    } 

    return fields; 
}

vector.c

Vector *vectorAlloc(size_t elemSize, VectorFreeFunction freeFunc) { 
    Vector *vector = malloc(sizeof(Vector)); 
    if (vector == NULL) { 
     fatalError("Cannot allocate vector"); 
    } 

    vector->capacity = DEFAULT_CAPACITY; 
    vector->size = 0; 
    vector->elemSize = elemSize; 

    vector->elements = malloc(elemSize * vector->capacity); 
    if (vector->elements == NULL) { 
     fatalError("Cannot allocate elements array of the vector"); 
    } 

    vector->freeFunc = freeFunc; 
    return vector; 
} 

void *vectorAt(Vector *vector, int position) { 
    assert(position < vector->size && position >= 0); 
    return ((char*)vector->elements + (position * vector->elemSize)); 
} 

void vectorPush(Vector *vector, const void *element) { 

    if (vector->size == vector->capacity) { 
     _vectorDoubleCapacity(vector); 
    } 

    void *destAddr = (char*)vector->elements + vector->size * vector->elemSize; 
    memcpy(destAddr, element, vector->elemSize); // add to end of vector 

    vector->size++; 
} 

void _vectorDoubleCapacity(Vector *vector) { 
    vector->capacity *= 2; 

    vector->elements = realloc(vector->elements, vector->elemSize * vector->capacity); 
    if (vector->elements == NULL) { 
     fatalError("Resizing the capacity of vector fails"); 
    } 
}

來源

2016-08-01 Lesley Lai

你的頭腦創造了[___MCVE___（http://stackoverflow.com/help/mcve）？ –

這太小了，例如Vector'定義缺失。 –

我不會將elemSize用於兩種不同的事情。但是你對有關字符串大於8字節的問題的評論很有啓發。我現在應該檢查一下。 –

你推到Vector的元素是指針到陣列指向的line參數getfields。以這種方式跟蹤元素的生命週期很困難，您應該在創建Vector時將分配的令牌副本分配爲strdup()並將free作爲VectorFreeFunction。

Futhermore，vectorAt返回一個指針向量元素，這本身就是一個char *，你用它來打印Vector內容的方式不正確：你應該投它作爲(char **)和取消對它的引用。

這裏是一個修正版本：

Vector *getfields(char *line) { 
    int i = 0; 
    const char *token; 

    Vector *fields = vectorAlloc(sizeof(char*), free); 

    for (token = strtok(line, ","); 
     token && *token; 
     token = strtok(NULL, ",\n"), i++) { 
     vectorPush(fields, strdup(token)); 
    } 

    for (int i = 0; i < fields->size; i++) { 
     printf("Field %d would be %s\n", i, *(char **)vectorAt(fields, i)); 
    } 

    return fields; 
}

來源

2016-08-01 12:07:14 chqrlie

爲什麼輸出字符串以奇怪的方式連接？

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