/* fichero invers2.c */
#include <stdio.h>
#include <stdlib.h>
void main(void)
{
    int ch;
    char texto[100];
    int i, n, dif;
    FILE *fi;
    fi = fopen("texto.d","r+");
    dif = 'a' - 'A';
    i = 0;
    while ((ch = getc(fi)) != EOF) {
        if ((ch >= 'a')&&(ch <= 'z'))
            ch -= dif;
        else if ((ch >= 'A')&& ch <= 'Z'))
            ch += dif;
        texto[i] = ch;
        i++;
    }
    texto[i] = '\0';
    for (n=i; n>=0; n--)
        putc(texto[n], fi);
    fclose(fi);
}