C-C编程：fopen打开镜像文件，检索关键字“idx1”，失败

Question

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "Search.h"

int main(){
    char buffer[4096];
    char *keyword="idx1";
    int location,count=1;
    FILE *fp=fopen("E:\dfrws-2007-challenge\dfrws-2007-challenge.img","rb");
    fseek(fp,0,SEEK_SET);
    if(fp==NULL){
        printf("cannot open the file");
    }
    else{
        while(!feof(fp)){
            
            fread(buffer,1,4096,fp);
            location=kmp(buffer,keyword);
            if(location!=-1)
                printf("location=%dn",location);
        }
    }
    fclose(fp);
    system("pause");
    return 0;
}

 
Search.h
#include <iostream>

using namespace std;

int kmp(char* str, char* pattern)
{
    if(str == NULL || pattern == NULL)
        return -1;
    int p_len = strlen(pattern);
    int* next = new int[p_len];
    next[0] = -1;
    for(int i=1; i<p_len; ++i)
    {
        int pre = next[i-1];
        while(pre>=0&&pattern[pre+1]!=pattern[i])
            pre = next
;
        if(pattern[pre+1] == pattern[i])
            next[i] = pre+1;
        else
            next[i] = -1;
    }
    
    int i =0 , j=0;
    int str_len = strlen(str);
    while(j<str_len)
    {
        while(i<p_len&&j<str_len&&pattern[i] == str[j])
            ++i,++j;
        if(i==0)
            ++j;
        else if (i==p_len) 
            return j-p_len;
        
        else
           i = next[i-1]+1;
    }
    return -1;
}

              

Answer 1

你处理的是二进制文件（有很多''），而你的KMP算法实现里是根据''来判断字符串长度的，虽然你每次读4096字节但是KMP根据''截断处理了，没有处理到全部字符。

自己把长度传给kmp就可以了：

location=kmp(buffer, keyword, 4096, 4);

int kmp(char* str, char* pattern, int str_len, int p_len){
//其他相应的修改
}

（有3个idx1）