帮忙看看是什么导致程序中断异常的？

[wonxlei]

各位帮忙调试下，我实在是找不到错误潜伏在哪～谢谢～
#include <iostream>
#include <vector>
using namespace std;

vector<int> vec;
vector<int>::iterator iter;
int i,j;
int* q;
int n;

int* putarr(int **p,int lhs,int rhs)
{ //lhs为行数，rhs为列数
if(i == 0)
{
if(j != (rhs-1))
{
q = &p[i][j+1];
*q = *iter;
iter ++;
return q;
}
q = &p[i+1][j];
*q = *iter;
iter ++;
return q;
}
else if(j ==(rhs-1))
{
if(i != (lhs-1))
{
q = &p[i+1][j];
*q = *iter;
iter ++;
return q;
}
q = &p[i][j-1];
*q = *iter;
iter ++;
return q;
}
else if(i ==(lhs-1))
{
if(j != 0)
{
q = &p[j][j-1];
*q = *iter;
iter ++;
return q;
}
q = &p[i-1][j];
*q = *iter;
iter ++;
return q;
}
else if(j == 0)
{
if(i != 0)
{
q = &p[i-1][j];
*q = *iter;
iter ++;
return q;
}
q = &p[i-1][j];
*q = *iter;
iter ++;
return q;
}
else
{
if((p[i-1][j] == 0)&&(p[i][j-1] != 0)&&(p[i+1][j] != 0)&&(p[i][j+1] != 0))
{
q = & p[i-1][j];
*q = *iter;
iter ++;
return q;
}
else if((p[i-1][j] != 0)&&(p[i][j-1] == 0)&&(p[i+1][j] != 0)&&(p[i][j+1] != 0))
{
q = &p[i][j-1];
*q = *iter;
iter ++;
return q;
}
else if((p[i-1][j] != 0)&&(p[i][j-1] != 0)&&(p[i+1][j] == 0)&&(p[i][j+1] != 0))
{
q = &p[i+1][j];
*q = *iter;
iter ++;
return q;
}
else if((p[i-1][j] != 0)&&(p[i][j-1] != 0)&&(p[i+1][j] != 0)&&(p[i][j+1] == 0))
{
q = &p[i][j+1];
*q = *iter;
iter ++;
return q;
}
else if((p[i-1][j] == 0)&&(p[i][j+1] == 0))
{
q = &p[i][j-1];
*q = *iter;
iter ++;
return q;
}
else if((p[i][j+1] == 0)&&(p[i+1][j] == 0))
{
q = &p[i][j+1];
*q = *iter;
iter ++;
return q;
}
else if((p[i+1][j] == 0)&&(p[i][j-1] == 0))
{
q = &p[i+1][j];
*q = *iter;
iter ++;
return q;
}
else if((p[i][j-1] ==0)&&(p[i-1][j] == 0))
{
q = & p[i-1][j];
*q = *iter;
iter ++;
return q;
}
else return q = 0;
}
}

int main()
{
i = 0;
j = 0;
cout << "输入数组的行数和列数n:" ;
cin >> n;
for(int z = 1; z != n*n + 1; ++z)
vec.push_back(z);
iter = vec.begin();
int** a = new int*[n];
for(int x = 0; x != n; ++x)
a[x] = new int[n];
for(int x = 0; x != n; ++x)
for(int y = 0; y != n; ++y)
a[x][y] = 0;
a[0][0] = 1;
q = &a[0][0];
while(q)
putarr(a,n,n);
for(int x = 0; x != n; ++x)
{
for(int y = 0; y != n; ++y)
cout << a[x][y] << " ";
cout << '\n';
}
for(int k = n; k != 0; --k)
delete []a[k-1];
delete []a;
return 0;
}

[lightnut]

while(q)
putarr(a,n,n);

====>
if(q)
putarr(a,n,n);

[lightnut]

main中的while(q), 无限循环, 最后iter就会无效了:)

[wonxlei]

好像不对啊～
在函数 putarr(int **p,int lhs,int rhs)
有语句return q = 0;
将q设置为0
怎么会无限循环呢～

[lightnut]

int* putarr(int **p,int lhs,int rhs)
{ //lhs为行数，rhs为列数
if(i == 0)
{
if(j != (rhs-1))
{
q = &p[i][j+1];
*q = *iter;
iter ++;
return q;
}
q = &p[i+1][j];
*q = *iter;
iter ++;
return q;
}
............
}

开始时 i==0; 执行putarr()中的if(i==0), 完后, i,j的值并没有修改, 下次进入, i还是0,
还是只执行if(i==0){}, 永远也不会执行到return q=0:!!!!

[wonxlei]

唉……
恍然大悟～

[珍惜生命远离CPP]

这么长.......

[wonxlei]

帮忙看看在函数int* putarr(int **p,int lhs,int rhs)中的第一个语句
iter ++;
网为什么导致了中断
谢谢～～～

[wonxlei]

全局变量iter在main函数中初始化了，
for(int z = 1; z != n*n + 1; ++z)
vec.push_back(z);
iter = vec.begin();
此时*iter的值应该是 1，
但是我设置断点调试的时候，好像是发现vec还是空的，不知道为什么……晕了