C++KMP算法的调试源代码

#include<iostream>
#include<malloc.h>
using namespace std;
typedef struct
{

	char data[20];
	int length;
}SqString;

void  GetNext(SqString t, int next[])
{
	int j, k;
	j = 0;
	k = -1;  next[0] = -1;
	while (j < t.length - 1)
	{
		if (k == -1 || t.data[j] == t.data[k])
		{
			j++; k++;
			next[j] = k;
			
		}
		else  k = next[k];  //k回退
	}
}

int KMPIndex(SqString s,SqString t)
{
	int next[20];
	int i = 0, j = 0;
	GetNext(t,next);
	while (i < s.length && j < t.length)
	{
		if (j == -1 || s.data[i] == t.data[j])
		{
			i++;
			j++;		//i、j各增1
		}
		else  j = next[j]; 	//i不变，j后退
	}
	if (j >= t.length)
		return(i - t.length);	//返回匹配模式串的首字符
	else
		return(-1);		//返回不匹配标志
}
void StrAssign(SqString& s, char cstr[],int len)
{
	
	int i;
	for ( i = 0; i< len; i++)
		s.data[i] = cstr[i];
	s.length = i;
 }
void DispStr(SqString s)
{
	int i;
	if (s.length > 0)
	{
		for (i = 0; i < s.length; i++)
			cout << s.data[i] << endl;
	}
}



int main()
{
	SqString pre;
	SqString fors;
	int nextpre[10];
	char prechar[] = { 'a','b','c','d','s','s' };
	char forschar[] = { 'c','d','s' };
	StrAssign(pre, prechar, sizeof(prechar) / sizeof(prechar[0]));
	StrAssign(fors, forschar, sizeof(forschar) / sizeof(forschar[0]));
	DispStr(pre);
	cout << endl;
	DispStr(fors);
	cout << KMPIndex(pre, fors);
	system("pause");
}