#include <iostream>
 
char * strToBinStr(char const * const src, char * const dest, size_t const size)
{
	char const * p = src;
	char c = '\0';
	size_t i = 0;
 
	if (size > 8)
	{
		while ((c = *p++) != '\0' && i < size-8)
		{
			for (int8_t j = 7; j >= 0; j--)
			{
				dest[i++] = ((c >> j) & 1) + '0';
			}
		}
	}
 
	dest[i] = '\0';
 
	return dest;
}
 
int main()
{
	char str[] = "Hi";
	char dest[17]; // enough space for 8*n characters + null character
 
	printf("%s\n", strToBinStr(str, dest, sizeof(dest)));
 
	return 0;
}

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