识别和打印整数的LEX代码&浮点常量和标识符

Integer - [0-9]+
Float - [0-9]+[.][0-9]+
Identifier - [A-Za-z_][A-Za-z0-9_]+


Input : 35
Output : Integer
Input : 3.98
Output : Float
Input : kashyap
Output : Identifier
Input : 123Singh
Output : Invalid


lex filename.l
cc lex.yy.c
./a.out


// Declaration Section
%{
%}
%s A B C DEAD        // Declaring states
// Rules Section
%%
<INITIAL>[0-9]+ BEGIN A;
<INITIAL>[0-9]+[.][0-9]+ BEGIN B;
<INITIAL>[A-Za-z_][A-Za-z0-9_]* BEGIN C;
<INITIAL>[^\n] BEGIN DEAD;
<INITIAL>\n BEGIN INITIAL; {printf("Not Accepted\n");}
<A>[^\n] BEGIN DEAD;
<A>\n BEGIN INITIAL; {printf("Integer\n");}
<B>[^\n] BEGIN DEAD;
<B>\n BEGIN INITIAL; {printf("Float\n");}
<C>[^\n] BEGIN DEAD;
<C>\n BEGIN INITIAL; {printf("Identifier\n");}
<DEAD>[^\n] BEGIN DEAD;
<DEAD>\n BEGIN INITIAL; {printf("Invalid\n");}
%%
// Auxillary Functions
int yywrap()
{
 return 1;
}
int main()
{
 printf("Enter String\n");
 yylex();
 return 0;
}


//Declaration Section
%{
#include
int num_int;            // stores integer
char *str;                // stores identifier
double num_float;        // stores float
%}
%s A B C DEAD        //Declaring States
//Rules Section
%%
<INITIAL> [0-9]+ BEGIN A;                    {num_int = atoi(yytext);}
<INITIAL> [0-9]+"."[0-9]+ BEGIN B;            {num_float = atof(yytext);}           
<INITIAL> [a-zA-Z_][a-zA-Z0-9_]* BEGIN C;    {str = yytext;}
<INITIAL> [^\n] BEGIN DEAD;
<INITIAL> [\n] BEGIN INITIAL;        {printf("Not Accepted\n");}
<A> [^\n] BEGIN DEAD;
<A> \n BEGIN INITIAL;        {printf("%d Integer Accepted\n", num_int);}
<B> [^\n] BEGIN DEAD;
<B> \n BEGIN INITIAL;        {printf("%lf Float Accepted\n", num_float);}
<C> [^\n] BEGIN DEAD;
<C> \n BEGIN INITIAL;        {printf("%sIdentifier Accepted\n", str);}
<DEAD> [^\n] BEGIN DEAD;
<DEAD> \n BEGIN INITIAL;    {printf("Invalid\n");}
%%
//Auxillary Functions
int yywrap()
{
      return 1;
}
int main(){
    printf("Enter String:\n");
     yylex();
     return 0;
}