struct Node
{
    Data *data;
    Node *next;
}

// this is efficient
for (int i=0; i< n; i++)
{
    strcat(str, data(i));
}

// this could be too, but you'd need to look at the implementation to be sure
std::string str;
for (int i=0; i<n; i++)
{
  str+=data(i);
}

String result = "";
for (int i = 1; i <= n; i++) {
    result = result + Integer.toString(i);
}

char *result = malloc(1);
*result = '';
for (int i = 1; i <=  n; i++) {
    char *intStr = malloc(11);
    itoa(i, intStr, 10);
    char *tempStr = malloc(/* some large size */);
    strcpy(tempStr, result);
    strcat(tempStr, intStr);
    free(result);
    free(intStr);
    result = tempStr;
}

a = a + b

def foo(l=[])
  l.append("bar")
  return l;