Memset.c

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

#define MAX_PASSWORD_LEN 100

void InputPassword(char *password)
{
  scanf("%s", password);
}

void ProcessPassword(char *password)
{
  printf("%s", password);
}

void Foo()
{
  char password[MAX_PASSWORD_LEN];
  InputPassword(password);
  ProcessPassword(password);
  memset(password, 0, sizeof(password));
}

int main() {
  Foo();
}