北航研究生複試2009上機第三題：字符串查找刪除

題目

給定文件filein.txt按照要求輸出fileout.txt.
輸入：無空格的字符串
輸出：將filein.txt刪除輸入的字符串(不區分大小寫)，輸出至fileout.txt。每行中的空格全部提前至行首。

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1、KMP匹配
2、不區分大小寫地比較
3、子串刪除
4、寫文件要求(空格提前)

---

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

char* filein = "filein.txt";
char* fileout = "fileout.txt";

char* GetFileContent(char* name);
void DeleteSubStr(char* pstr, char* sstr);
void GetNext(char* str, int len, int* next);
bool Equal(char a, char b);
void WriteFile(char* note, char* name);

int main(){

    char* note = GetFileContent(filein);

    char substr[100];
    printf("輸入要刪除的字符串：");
    scanf("%s",&substr);


    DeleteSubStr(note,substr);
    //printf("%s\n",note);
    WriteFile(note,fileout);

    return 0;
}

char* GetFileContent(char* name){
    FILE* fp;
    char* str;
    if((fp = fopen(name,"r")) == NULL){
        printf("The file %s can not be opened\n",name);
        exit(1);
    }
    int ch;
    int size = 0;
    while((ch = fgetc(fp)) != EOF)
        ++size;
    rewind(fp);

    str = (char* )malloc(sizeof(char) * size + 1);
    int i;
    for(i = 0; i < size; i++){
        ch = fgetc(fp);
        str[i] = ch;
    }
    str[size] = '\0';
    fclose(fp);
    return str;
}

bool Equal(char a, char b){
    if(b>= '0' && b<= '9')
        if(a == b)
            return true;

    if(b>='A' && b<='Z')
        if(a == b || a + 'A' - 'a' == b)
            return true;

    if(b>='a' && b<='z')
        if(a == b || a + 'a' - 'A' == b)
            return true;

    return false;
}

void GetNext(char* str, int len, int* next){
    if(len <= 0){
        printf("子串大小有誤\n");
        return ;
    }
    int i,j;
    next[0] = 0;
    i = 1;
    j = 0;
    for(; i < len; ){
        if(j == 0 || Equal(str[i - 1],str[j - 1])){
            next[i++] = ++j;
        }else{
            j = next[j - 1];
        }
    }
}

void DeleteSubStr(char* pstr, char* sstr){
    int plen = strlen(pstr);
    int slen = strlen(sstr);

    int* next = (int* )malloc(sizeof(int) * slen);
    GetNext(sstr,slen,next);

    int i,j;
    //for(i = 0; i < slen; i++)
    //  printf("%d ",next[i]);
    i = j = 0;
    while(i < plen && plen >= slen){
        if(Equal(pstr[i],sstr[j])){
            ++i;++j;
            if(j == slen){//刪除操作
                int begin = i - j;
                int end = i;
                for(; end < plen; end++)
                    pstr[begin++] = pstr[end];
                i -= j;
                plen -= j;
                j = 0;
            }
        }else{
            if(j == 0)
                ++i;
            else{
                j = next[j - 1];
            }
        }
    }
    pstr[plen] = '\0';
}

void WriteFile(char* note, char* name){
    FILE* fp;
    if((fp = fopen(name,"w")) == NULL){
        printf("The file %s can not be opened\n", name);
        exit(1);
    }

    int len = strlen(note);
    int count = 0;
    int begin,end;
    int j;
    begin = end = 0;
    while(begin < len){
        while(note[end] != '\n' && end < len){
            if(note[end] == ' '){
                ++count;
            }
            ++end;
        }
        for(j = 0; j < count; j++){
            fputc((int)(' '),fp);
        }
        for(j = begin; j <= end; j++){
            if(note[j] != ' '){
                fputc((int)(note[j]), fp);
            }
        }
        ++end;
        begin = end;
        count = 0;
    }

    fclose(fp);
}

filein.txt:
Who has seen the winD?
Neither I nor you;
But when the leaves hang trembling,
The wInd is passing through.
Who has seen the WIND?
Neither you nor I;
But when the trees bow down their heads,
The Wind is passing by.
–Christina Rossett

輸入的子串：
wind

fileout.txt