void write_char(char);
int len(char*);
void f(char *a)
{
int col = 0;
int i;
void wchar(char c)
if (c == '\t')
do {
wchar(' ');
} while ((col%8)!=0);
}
else
write_char (c);
col++;
for(i =0;i<len(a);i++)
wchar(*a);