Lexical Analysis Program

/*************************************** **********************/
/*
/* Lexical analysis program
/* Maker: Zhang jianbo
/* Date: 2005-10-26
/*
/*************************************** **********************/
# Include "stdio. H"
# Include "ctype. H"
# Include "string. H"

/* Number of reserved words */
# Define keywordsum 8
Char * keyword [keywordsum] = {"if", "else", "for", "while", "do", "int", "read ", "Write "};

/* Pure but single delimiters */
# Define singlewordsum 10
Char singleword [singlewordsum] = "+ -*(){};,:";

/* Dual delimiters */
# Define doublewordsum 4
Char doubleword [doublewordsum] = "<> =! ";

# Define wordlen 40/* maximum word length */

Char scaninfile [300];/* source program file to be analyzed */
Char scanoutfile [305];/* output file after lexical analysis */

File * fin, * fout;/* pointer to the input/output file */

Int loadcodefile ()
{
/* Open the source code file to be analyzed */

Printf ("Enter the source program file name :");
Scanf ("% s", scaninfile );
If (fin = fopen (scaninfile, "R") = NULL)
{
Printf ("/n cannot find the file: % s/n file opening failed! /N ");
Return 0;
}
Else
Return 1;
}

Int creatwordfile ()
{
/* Output file after the lexical analysis is created */
Int Len = 0;
Int I = 0;
Strcpy (scanoutfile, scaninfile );
While (scanoutfile [I ++]! = '.');
Scanoutfile [I + 1] ='s ';
Scanoutfile [I + 2] = 'C ';
Scanoutfile [I + 3] = 'n ';
Scanoutfile [I + 4] = '/0 ';
If (fout = fopen (scanoutfile, "W") = NULL)
{
/* File creation failed */
Return 0;
}
Else
Return 1;

}

/* Lexical analysis program */
Int tscan ()
{

Char CH, Token [wordlen];/* Ch is the character read each time, and token is the recognized word */

Char comment;/* temporary variable used to process comments */

Int err = 0;/* set error code to 0, indicating no error */
Int J, N;/* temporary variable, control the array subscript when combining words */

If (loadcodefile () = 0)
Return 1;/* failed to read the source code file */
If (creatwordfile () = 0)
Return 2;/* file creation failed */

Ch = GETC (FIN );
While (Ch! = EOF)
{
While (CH = ''| CH = '/N' | CH ='/t ')
{
Ch = GETC (FIN );
}
If (isalpha (CH ))
{
/* Enter a letter to process the identifier */
Token [0] = CH;
J = 1;
While (isalnum (CH ))
{
Token [J ++] = CH;
Ch = GETC (FIN );
}/* A combination of letters and numbers. Otherwise, the combination ends */
Token [J] = '/0 ';
/* Search for reserved words */
N = 0;
While (n <keywordsum) & strcmp (token, keyword [N])
N ++;
If (n> = keywordsum)
{
/* Output identifier */
Fprintf (fout, "% S/T % s/n", "ID", token );
Printf ("% S/T % s/n", "ID", token );
}
Else
{
/* Output reserved words */
Fprintf (fout, "% S/T % s/n", Token, token );
Printf ("% S/T % s/n", Token, token );
}
}
Else if (isdigit (CH ))
{
/* Enter a number for processing */
Token [0] = CH;
J = 1;
Ch = GETC (FIN);/* read the next character */
While (isdigit (CH ))
{/* Merge numbers if they are numbers */
Token [J ++] = CH;
Ch = GETC (FIN );
}
Token [J] = '/0';/* integer consolidation ends */
Fprintf (fout, "% S/T % s/n", "num", token );
Printf ("% S/T % s/n", "num", token );
}
Else if (strchr (singleword, CH)> 0)
{
/* The input is a single separator */
Token [0] = CH;
Token [1] = '/0 ';
Ch = GETC (FIN );
Fprintf (fout, "% S/T % s/n", Token, token );
Printf ("% S/T % s/n", Token, token );
}
Else if (strchr (doubleword, CH)> 0)
{
/* Double delimiters are input */
Token [0] = CH;
Ch = GETC (FIN );
If (CH = ')/* If yes =, combine the dual delimiters */
{
Token [1] = CH; token [2] = '/0 ';
Ch = GETC (FIN );
}
Else
{
Token [1] = '/0 ';
}
Fprintf (fout, "% S/T % s/n", Token, token );
Printf ("% S/T % s/n", Token, token );
}
Else if (CH = '/')
{
/* Comment Processing */
Ch = GETC (FIN );
If (CH = '*')
{
Response = GETC (FIN );
Do
{
Ch = success;
Response = GETC (FIN );
} While (Ch! = '*' | Success! = '/') & Amp; success! = EOF );
Ch = GETC (FIN );
}
Else
{
Token [0] = '/';
Token [1] = '/0 ';
Fprintf (fout, "% S/T % s/n", Token, token);/* output word delimiters */
Printf ("% S/T % s/n", Token, token );
}
}
Else
{
/* Unrecognized characters */
Token [0] = CH;
Token [1] = '/0 ';
Ch = GETC (FIN );
Err = 3;
Fprintf (fout, "% S/T % s/n", "error", token);/* output error symbol */
Printf ("% S/T % s/n", "error", token );
}
}
Return err;
}

Void main ()
{
Int e = 0;
E = tscan ();
If (E> 0) printf ("Compilation error! ");
Else
Printf ("lexical analysis successful! ");

}