串的模式匹配算法(求子串位置的定位函数,适合一般字符串定位)

SString.h

 

#ifndef SSTRING_H_H#define OK0#defineERROR-1#define MAX_LENGTH255typedef unsigned char SString[MAX_LENGTH + 1];//第0个位置存放串的长度int sstr_assign(SString, const char*);int sstr_index(SString, SString, int);int sstr_print(SString);#endif

 

Index.cpp

 

#include<stdio.h>#include<stdlib.h>#include"SString.h"//产生一个SString类型的串，其值等于sstrint sstr_assign(SString T, const char *sstr){int ix = 0;while(sstr[ix] != '/0'){T[ix + 1] = sstr[ix++];//如果空间耗尽，则不再复制。if(ix == MAX_LENGTH)break;}//保存串的长度T[0] = ix;return OK;}int sstr_index(SString T, SString S, int pos){/* 在一般情况下，算法的时间复杂度为O(ix + jx) */if(0 == T[0] || 0 == S[0]|| pos > T[0] || pos < 1)return ERROR;int ix = pos;int jx = 1;while(ix <= T[0] && jx <= S[0]){if(T[ix] == S[jx]){ix++;jx++;}else{//指针回退，再重新比较ix = ix - jx + 2;jx = 1;}}if(jx > S[0])return ix - S[0];//用ix在T中的位置减去S的长度 == 首个字符串匹配的位置return OK;}int sstr_print(SString T){int cnt = T[0];int ix = 1;while(cnt-- > 0){printf("%c",T[ix++]);}printf("/n");return OK;}

 

Main.cpp

 

#include<stdio.h>#include<stdlib.h>#include"SString.h"void main(){SString s1,s2;sstr_assign(s1,"abcdefghij");sstr_assign(s2,"fghi");int pos = sstr_index(s1,s2,2);printf("%d/n", pos);}