Compiler Principle lexical analysis-recursive descent Analysis

# Include <iostream. h>
# Include <stdlib. h>
# Include <fstream. h>

Char sym = '#';
Int iws = 1;
Char wordstring [100];
Int flag = 1;

Void advance (void); void Fe (void );
Void fe1 (void); void ft (void );
Void FT1 (void); void ff (void );
Void erroryf (void );

Void erroryf (void)
{
Flag = 0;
Cout <"error! ";
Cout <Endl <iws <Endl;
}
Void advance (void)
{
If (wordstring [iws] = '/0 ')
{
Sym = '#';
Return;
}
// If (wordstring [iws] = '0 ')
Sym = wordstring [iws ++];
// Cout <"sym =" <sym <Endl;
 
}
Void Fe (void)
{
Ft ();
Fe1 ();
// Cout <"End of Fe"; cout <Endl;
}
Void fe1 (void)
{
If (sym = '+ ')
{
Advance ();
If (sym = '#')
{
Return;
}
Ft ();
Fe1 ();
}
}
Void ft (void)
{
Ff ();
FT1 ();
}
Void FT1 (void)
{
If (sym = '*')
{
Advance ();
If (sym = '#')
{
Return;
}
Ff ();
FT1 ();
}
}
Void ff (void)
{
If (sym = 'I ')
{
Advance ();
If (sym = '#')
{
Return;
}
}
Else if (sym = '(')
{
Advance ();
If (sym = '#')
{
Return;
}
Fe ();
If (sym = ')')
{
Advance ();
If (sym = '#')
{
Return;
}
}
Else
{
Erroryf ();
}
}
Else
{
Erroryf ();
}
}

Main ()
{
Cin> wordstring;
Sym = wordstring [0];
Fe ();
If (FLAG)
Cout <wordstring <"is riyun! ";
Cout <Endl;
Return (0 );
}