Esercizio Fscanf

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_LEN 64

void reverse_string(char [MAX_LEN], int);

main(){
    FILE * fp;
    char string[MAX_LEN];
    ((fp=fopen("testo.txt", "r"))!=NULL)?:(exit(1));
    while(feof(fp)==0){
        fscanf(fp, "%63[a-zA-Z]%*[^a-zA-Z]", string);
        reverse_string(string, strlen(string));
        printf("%s %d\n", string, (int)strlen(string));
    }
    return 0;
}

void reverse_string(char str[MAX_LEN], int size){
    int i;
    for(i=0;i<size/2;i++)
        str[i]^=str[size-i-1]^=str[i]^=str[size-i-1];
}