Question

我正在尝试使用malloc来创建一个我不断收到此错误的数组。

严重级代码说明项目文件行警告C4047'='：'DynamicArray *'的间接水平与'double **'cStudy 19不同

严重级代码说明项目文件行警告C4133'初始化'：不兼容的类型 - 从'int *'到'double *'cStudy 36

 typedef struct
{
double *arrayPointer;
int effectiveSize;
int maximumSize;
} DynamicArray;

void CreateArray(DynamicArray *mArray, int initialSize)
{ 
//TODO: Use malloc to create an array of the initial size.  Assign to   the arrayPointer variable

//TODO: Set effective size to 0 and maximum size to the initial size
mArray->arrayPointer = malloc(initialSize *sizeof(double));
mArray->effectiveSize = 0;
mArray->maximumSize = initialSize;
}

void ExpandArray（DynamicArray * mArray，int newSize） {

    double* newArray;

    mArray->arrayPointer = newArray = (int *)malloc(newSize * sizeof(double));
    memcpy(newArray, &mArray[mArray->effectiveSize], mArray->effectiveSize * sizeof(double));


    free(mArray->arrayPointer);
    //mArray->effectiveSize = 0;
    mArray->maximumSize = newSize;

}

更新了代码，但展开不起作用。

Answer 1

此作业

mArray = (double *)malloc(initialSize * sizeof(double *));

应该是

mArray->arrayPointer = malloc(initialSize * sizeof(double));

需要进行一些更改：

sizeof应该是double，而不是double*
作业应该是mArray->arrayPointer，而不是mArray本身。
C中不需要强制转换为double*。

关于施法的观点也适用于这一行：

double* newArray = (int *)malloc(newSize * sizeof(double));

但请注意，ExpandArray可能会使用realloc，而不是普通malloc。

Answer 2

我想通了：D

double * newArray = malloc(sizeof(double)* newSize);
memcpy(newArray, mArray->arrayPointer, newSize * sizeof *newArray);
free(mArray->arrayPointer);
mArray->maximumSize = newSize;
mArray->arrayPointer = newArray;

我只需要更多的咖啡。

C中的Dyamic双数组

2 个答案: