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

int swap_2symb(char* a, char* b)
{
	char t = *a;
	*a = *b;
	*b = t;
	return 0;
}

int reverse_in_place(char* s, size_t p)
{
	for (size_t i=0; i < p / 2; ++i)
		swap_2symb(s + i, s + p - 1 - i);

	return 0;
}


int main()
{
	char s[] = "Hello, Embarcadero";
	printf("before: %s\n", s);
	reverse_in_place(s, strlen(s));
	printf("after: %s\n", s);
	return 0;
}

#include <stdio.h>


size_t strlen(const char* s)
{
	size_t p = 0;
	while (*s++)
		++p;

	return p;
}

int reverse_in_place(char* res, const char* s, size_t p)
{
	for (size_t i = 0; i < p; ++i)
		*(res + p - 1 - i) = *(s + i);

	*(res + p) = '\0';
	return 0;
}

char* reverse(const char* s)
{
	size_t p = strlen(s);
	char* res = (char*)malloc(sizeof(char)*(p+1));
	reverse_in_place(res, s, p);
	return res;
}

int reverse_in_place(char* res, const char* s, size_t p)
{
	for (int i = p - 1; i >= 0; --i)
		*res++ = *(s + i);

	*res = '\0';
	return 0;
}

int my_printf(FILE* out, const char* s, size_t p, int(*func)(const char* s, size_t p, int i))
{
	for (int i = 0; i < p; ++i)
		putc(func(s,p,i), out);

	return 0;
}

//function is defined on i in[0,p)
//reverse(x)
int reverse(const char* s, size_t p, int x)
{
	return *(s + p - 1 - x);
}




int main()
{
	char s[] = "Hello, Embarcadero";
	printf("before: %s\n", s);
	size_t p = strlen(s);
	my_printf(stdout, s, p, (*reverse));
	printf("\n");
	return 0;
}