If the size of the space requested is zero, the behavior is implementation-defined: either a null pointer is returned, or the behavior is as if the size were some nonzero value, except that the returned pointer shall not be used to access an object.
if (strcmp(word, "apple") == 0) { flag = TRUE; else if (strcmp(word, "orange") ==0) { flag = TRUE; else if (strcmp(word, "lemon") ==0) { flag = TRUE; }