#include <stdio.h>
#include <stdlib.h>
int error(const char *message)
{
fprintf(stderr, "\nError: %s.\n", message);
return EXIT_FAILURE;
}
void scan_string(char *buffer, unsigned length) {
char format[12]; // Support max int value for the format %<num>s
snprintf(format, sizeof(format), "%%%ds", length - 1); // Generate format
scanf(format, buffer);
}
int main()
{
char bits[128];
printf("Enter one or more binary bits: ");
scan_string(bits, sizeof(bits));
int ones = 0;
for (const char *bitp = bits; *bitp != '\0'; ++bitp)
{
if (*bitp == '1')
++ones;
else if (*bitp != '0')
return error("invalid input");
}
char result = (ones%2==0) ? '0' /*even*/ : '1' /*odd*/;
printf("The result is: %s%c", bits, result);
return EXIT_SUCCESS;
}
