[VC MFC C++ flex bison] flex example(Pascal-like language scanner)

//scanner.l

%{
/* need this for the call to atof() below */
#include <math.h>
%}

DIGIT    [0-9]
ID       [a-z][a-z0-9]*

%%

{DIGIT}+    {
            printf( "An integer: %s (%d)/n", yytext,
                    atoi( yytext ) );
            }

{DIGIT}+"."{DIGIT}*        {
            printf( "A float: %s (%g)/n", yytext,
                    atof( yytext ) );
            }

if|then|begin|end|procedure|function        {
            printf( "A keyword: %s/n", yytext );
            }

{ID}        printf( "An identifier: %s/n", yytext );

"+"|"-"|"*"|"/"   printf( "An operator: %s/n", yytext );

"{"[^}/n]*"}"     /* eat up one-line comments */

[ /t/n]+          /* eat up whitespace */

.           printf( "Unrecognized character: %s/n", yytext );

%%

main( argc, argv )
int argc;
char **argv;
    {
    ++argv, --argc;  /* skip over program name */
    if ( argc > 0 )
            yyin = fopen( argv[0], "r" );
    else
            yyin = stdin;

    yylex();
    }

 

以下方法產生:

fl scanner