串朴素模式匹配算法实现

#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>


#define MAXSTRLEN 255

// 存储结构
typedef unsigned char SString[MAXSTRLEN + 1];

// 朴素匹配模式
int Index(SString S, SString T, int pos){
    int i = pos;
    int j = 1;
    while(i<S[0] && j<=T[0]){
        if(S[i] == T[j]){
            ++i;
            ++j;
        }else{
            i = i-j+2;
            j = 1;
        }
    }
    if(j>T[0]){
        return i-T[0];
    }
    return 0;
}

bool StrAssign(SString str, char *src){
    char * c = src;
    for(int i=0; *c!='\0'; ++i, ++c){
        if(0==i){
            str[0] = 0;
        }else{
            str[0] = 0;
            for(int j=1; j<=i; j++){
                str[j] = src[j-1];
                str[0] +=1;
            }
        }
    }
}

void main(){
    SString S;
    SString T;
    char a[] = "abbacdefg";
    char b[] = "acd";
    // 给串分配元素顺便牺牲掉第一个位置来记录串的实际长度
    StrAssign(S, a);
    StrAssign(T, b);
    int pos = Index(S, T, 3);
    if (pos != 0)
        printf("模式匹配成功，找到位置为%d\n", pos);
    else
        printf("模式匹配失败");
    return 0;
}