函数的调用问题

Synopsis

先来看两个错误

1. 报错

   'insertList' was not declared in this scope

2. 修改没有加引用型&的参数

Detail

1. 第一个错误，显然是这个函数没有被定义。但我已经创建了呀！！这又是为什么呢？经过回忆，是因为在函数A调用函数B的时候，把函数A放在函数B的前面。又因为，程序是从上到下执行的，所以才会报错成未定义。

2. 这个在修改参数中，经常用到。而且这是一个很常见又很严重的错误。因为参数的传递的将参数值复制过去另外一个块中。一开始学c的时候，用到了地址的传递（也就是传指针）。现在c++中修改参数，就不必再传指针了，不过要记得要改成引用型啊。

#include<iostream>
using namespace std;
#define MAXSIZE 100
typedef int ElemType;
typedef struct SqList
{  ElemType data[MAXSIZE];
   int length;
}SqList;

int insertList(SqList *sq,int i,ElemType x)
{	int j;
	if(i<0||i>sq-> length -1)
	{	printf("\n The value of %d is wrong!\n", i);
		return 0;
	}
	if(sq-> length >= MAXSIZE)
	{	printf("\n overflow!");
  		return 0;
	}
	for(j=sq->length-1;j>=i;j--)
		sq->data[j+1]=sq->data[j];
	sq->data[i]=x;
	sq->length++;
	return 1;
}

int deleteList(SqList *sq,int i)
{	if(i<0 || i>sq-> length)
	{	printf("\n the position is wrong!\n");
		return 0;
	}
	for(i;i<sq->length;i++)
		sq->data[i-1]=sq->data[i];
	sq->length--;
	return 1;
}

void createList(SqList &L)
{
    ElemType e;
    int n;
    cout << "Please enter the length of the list: ";
    cin >> n;
    cout << "Enter " << n << " numbers: ";
    for(int i=0; i < n; i++){
        cin>>e;
        L.data[i]=e;
    }
    L.length=n;
}

void insert(SqList &L)
{
    int i, j;
    cout << "Please enter the index that needs to insert(start from 0): ";
    cin >> i;
    cout << "Please enter the data that needs to insert: ";
    cin >> j;
    insertList(&L, i, j);
}

void delet(SqList& L)
{
    int i;
    cout << "Please enter the index that needs to delet(start from 0): ";
    cin >> i;
    deleteList(&L, i);
}

void print(SqList &L)
{
    int i;
    cout << "list: ";
    for(i=0; i< L.length;i++)
    {
        cout << L.data[i] << " ";
    }
    cout << endl;
}


int main()
{
    SqList L;
    ElemType i,j;

    createList(L);
    print(L);
    
    insert(L);
    print(L);

    delet(L);
    print(L);

    system("pause>0");
}