c - 静态、堆栈和堆分配有何不同？

Question

我怎样才能声明这样一个数组:

int array[1000000];

作为静态数组、堆栈数组和堆分配数组？

Answer 1

您的任务似乎是在寻找这个:

// global variable; NOT on the stack. Exists in the data segment of the program
int globalvar[1000000];

void func()
{
    // local stack-variable. allocated on the stack on function entry
    //  unavailable outside this function scope.
    int stackvar[1000000];

    // allocated on the heap. the only stack space used in the
    //  space occupied by the pointer variable.
    int *heapvar = malloc(1000000 * sizeof(int));
    if (heapvar != NULL)
    {
        // use heap var

        // free heap var
        free(heapvar)
    }
}

或者也许是这样的:

void func()
{
    // static variable; NOT on the stack. Exists in a program data segment (usually)
    static int staticvar[1000000];
    
    // local stack-variable. allocated on the stack on function entry
    //  unavailable outside this function scope.
    int stackvar[1000000];

    // allocated on the heap. the only stack space used in the
    //  space occupied by the pointer variable.
    int *heapvar = malloc(1000000 * sizeof(int));
    if (heapvar != NULL)
    {
        // use heap var

        // free heap var
        free(heapvar)
    }
}

就其值(value)而言，除非您有一个 4 或 8 兆字节的保留调用堆栈(或更大)，否则上面的函数可能会在输入时出错。对于如此大的尺寸，通常使用堆 (malloc()/free())。但这似乎不是您的任务(目前)的内容。