动态数组分配与回收

[mz5052]

下面是一个kmp算法的实现，大家不用管算法的具体思路。现在的问题是程序一直无法出结果，我调试的时候发现卡在kmp_matcher()里面的delete [] next;这条语句。不是很明白为什么会卡在这里，求大神指导。

#include <iostream>
#include <string>
using std::cin;	using std::cout;	using std::endl;
using std::string;

int* get_next( const string& s );
int kmp_matcher( const string& txt , const string& pat );

int main( void )
{
	string txt = "ababcabcacbab";
	string pat = "abcac";
	
	int loc = kmp_matcher( txt , pat );
	
	cout << loc << endl;

	return 0;
}

int* get_next( const string& s )
{
	int N = s.size();
	int* next = new int[N];
	if( NULL == next )
		return NULL;

	int i = 0;
	int j = -1;
	next[ 0 ] = -1;

	while( i < N )
	{
		if( -1 == j || s[ i ] == s[ j ] )
		{
			++i;
			++j;
			next[ i ] = j;
		}
		else
			j = next[ j ];
	}
	return next;
}
int kmp_matcher( const string& txt , const string& pat )
{
	int N = txt.size();
	int M = pat.size();

	if( 0 == N || 0 == M )
		return -1;

	int* next = get_next( pat );
	
	int i = 0 , j = 0;
	while( i < N && j < M )
	{
		if( txt[ i ] == pat[ j ] )
		{	++i;++j;}
		else
			j = next[ j ];
	}

	delete [] next;

	if( M == j )
		return i - M;
	else
		return -1;
}

[fly_dragon_fly]

get_next中 ++i; ++j; next[ i ] = j; 这地方会越界

[张小飞Official]

这编码风格我也是醉了。。。双层循环注意越界问题！

[zhouxiaofeng1021]

你的代码写的不符合规范 建议你看看代码编写规范标准 而且很容易出现边界问题 同时呢，你这个int* next = get_next( pat ); 从函数get_next 返回的是 new 还是new[] 这个对于new后的内存地址会有一个内存位置表示是单个还是数组 我调试了下 _RPT3(_CRT_ERROR, "HEAP CORRUPTION DETECTED: after %hs block (#%d) at 0x%p.\n" "CRT detected that the application wrote to memory after end of heap buffer.\n", szBlockUseName[_BLOCK_TYPE(pHead->nBlockUse)], pHead->lRequest, (BYTE *) pbData(pHead)); 到这里 http://blog.csdn.net/wu_lai_314/article/details/8241697 看一下 你这个是内存操作越界问题

[zhouxiaofeng1021]

int* get_next( const string& s ) { int N = s.size(); int* next = new int[N*2]; //这里改了一下 OK了 if( NULL == next )