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

void show(char *s1, char *s2);
int check_memory(char *str);

int main(void)
{
    char *s1, *s2;
    s1 = (char*)malloc(256 * sizeof(char));
    check_memory(s1);

    s2 = (char*)malloc(256 * sizeof(char));
    check_memory(s2);

    printf("Введите строку:\n");
    fgets(s1, 256, stdin);

    show(s1, s2);
    printf("Скрытые символы : %s\n", s2);
    free(s1);
    free(s2);
    return 0;
}

void show(char *s1, char *s2) {
    int i, j, k = 0;
    for (i = 0; s1[i] != '\0'; i++) {

        if (s1[i] == '-') {

            if (s1[i - 1] < s1[i + 1]) {
                for (j = s1[i - 1]; j <= s1[i + 1]; j++)
                    s2[k++] = j;

            } else if (s1[i - 1] > s1[i + 1]){
                for (j = s1[i - 1]; j >= s1[i + 1]; j--)
                    s2[k++] = j;
            }
            s2[k] = ' ';
            k++;
        }
    }
    s2[k] = '\0';
}

int check_memory(char *str){
    if (str == NULL)
        return EXIT_FAILURE;
    return EXIT_SUCCESS;
}