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

void get_word(char *s, int *pos, char *w) {
    int n = strlen(s);
    int i = 0;

    while (*pos < n && s[*pos] <= ' ') {
        ++*pos;
    }

    while (*pos < n && s[*pos] > ' ') {
        w[i] = s[*pos];
        i++;
        ++*pos;
    }
    w[i] = '\0';
}

void new_text(char *fname, char *str){
    FILE *F;
    long startpos,stoppos;
    char s[250],
         word[20];

    int pos=0,n;
    F = fopen(fname, "r+");
    startpos=ftell(F);
    while ( fgets(s, 100, F)   ) {
        puts(s);
        fseek(F,startpos,SEEK_SET);
        printf("%li\n",startpos);

        char news[200]={""} ;
        n = strlen(s);
        while (pos < n) {
            get_word(s, &pos, word);
            if (strstr(word,str)!=NULL){
                strcat(news,word);
                strcat(news," ");
               // puts(news);
            }
        }

        fprintf(F,"%s\n",news);
        startpos=ftell(F);
      fseek(F,startpos,SEEK_SET);
        pos=0;
    }
}

int main() {
    char fname[20]="g.txt",
         STR[]="dv";
    //gets(fname);

    new_text(fname,STR);


    return 0;
}