Esercizio Doppie

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#define MAX_LEN 32
/* leggi le parole, se contengono doppie, rendile singole */
void rimuovi_doppie(char *, int);

main(){
    FILE * fi, * fo;
    char string[MAX_LEN], filename[MAX_LEN];
    puts("Gimme filename");
    scanf("%s", filename);
    ((fi=fopen(filename, "r"))!=NULL)?:(exit(1));
    ((fo=fopen("output.txt", "w"))!=NULL)?:(exit(1));
    while(!feof(fi)){
        fscanf(fi, "%s", string);
        if((isupper(string[0]))!=0){
            rimuovi_doppie(string, strlen(string));
            fprintf(fo, "%s\t", string);
        }
    }
    fclose(fi);
    fclose(fo);
    return 0;
}

void rimuovi_doppie(char * str, int size){
    void shift_left_string(char *, int, int);
    int i;
    for(i=0;i<size;i++)
        if(str[i]==str[i+1])
            shift_left_string(str, i+1, size);
}

void shift_left_string(char * str, int start, int size){
    int i;
    for(i=start;i<=size;i++)
        str[i]=str[i+1];
}