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/*
* numbers.lex : An example of the definitions and techniques
* for scanning numbers
*/
%{
#include <stdio.h>
#define UNSIGNED_LONG_SYM 1
#define SIGNED_LONG_SYM 2
#define UNSIGNED_SYM 3
#define SIGNED_SYM 4
#define LONG_DOUBLE_SYM 5
#define FLOAT_SYM 6
union _yylval {
long double ylong_double;
float yfloat;
unsigned long yunsigned_long;
unsigned yunsigned;
long ysigned_long;
int ysigned;
} yylval;
%}
digit [0-9]
hex_digit [0-9a-fA-F]
oct_digit [0-7]
exponent [eE][+-]?{digit}+
i {digit}+
float_constant ({i}\.{i}?|{i}?\.{i}){exponent}?
hex_constant 0[xX]{hex_digit}+
oct_constant 0{oct_digit}*
int_constant {digit}+
long_ext [lL]
unsigned_ext [uU]
float_ext [fF]
ulong_ext {long_ext}{unsigned_ext}|{unsigned_ext}{long_ext}
%%
{hex_constant}{ulong_ext} { /* we need to skip the "0x" part */
sscanf(&yytext[2],"%lx",&yylval.yunsigned_long);
return(UNSIGNED_LONG_SYM);
}
{hex_constant}{long_ext} {
sscanf(&yytext[2],"%lx",&yylval.ysigned_long);
return(SIGNED_LONG_SYM);
}
{hex_constant}{unsigned_ext} {
sscanf(&yytext[2],"%x",&yylval.yunsigned);
return(UNSIGNED_SYM);
}
{hex_constant} { /* use %lx to protect against overflow */
sscanf(&yytext[2],"%lx",&yylval.ysigned_long);
return(SIGNED_LONG_SYM);
}
{oct_constant}{ulong_ext} {
sscanf(yytext,"%lo",&yylval.yunsigned_long);
return(UNSIGNED_LONG_SYM);
}
{oct_constant}{long_ext} {
sscanf(yytext,"%lo",&yylval.ysigned_long);
return(SIGNED_LONG_SYM);
}
{oct_constant}{unsigned_ext} {
sscanf(yytext,"%o",&yylval.yunsigned);
return(UNSIGNED_SYM);
}
{oct_constant} { /* use %lo to protect against overflow */
sscanf(yytext,"%lo",&yylval.ysigned_long);
return(SIGNED_LONG_SYM);
}
{int_constant}{ulong_ext} {
sscanf(yytext,"%ld",&yylval.yunsigned_long);
return(UNSIGNED_LONG_SYM);
}
{int_constant}{long_ext} {
sscanf(yytext,"%ld",&yylval.ysigned_long);
return(SIGNED_LONG_SYM);
}
{int_constant}{unsigned_ext} {
sscanf(yytext,"%d",&yylval.yunsigned);
return(UNSIGNED_SYM);
}
{int_constant} { /* use %ld to protect against overflow */
sscanf(yytext,"%ld",&yylval.ysigned_long);
return(SIGNED_LONG_SYM);
}
{float_constant}{long_ext} {
sscanf(yytext,"%lf",&yylval.ylong_double);
return(LONG_DOUBLE_SYM);
}
{float_constant}{float_ext} {
sscanf(yytext,"%f",&yylval.yfloat);
return(FLOAT_SYM);
}
{float_constant} { /* use %lf to protect against overflow */
sscanf(yytext,"%lf",&yylval.ylong_double);
return(LONG_DOUBLE_SYM);
}
%%
int main(void)
{
int code;
while((code = yylex())){
printf("yytext : %s\n",yytext);
switch(code){
case UNSIGNED_LONG_SYM:
printf("Type of number : UNSIGNED LONG\n");
printf("Value of number : %lu\n",yylval.yunsigned_long);
break;
case SIGNED_LONG_SYM:
printf("Type of number : SIGNED LONG\n");
printf("Value of number : %ld\n",yylval.ysigned_long);
break;
case UNSIGNED_SYM:
printf("Type of number : UNSIGNED\n");
printf("Value of number : %u\n",yylval.yunsigned);
break;
case SIGNED_SYM:
printf("Type of number : SIGNED\n");
printf("Value of number : %d\n",yylval.ysigned);
break;
case LONG_DOUBLE_SYM:
printf("Type of number : LONG DOUBLE\n");
printf("Value of number : %lf\n",yylval.ylong_double);
break;
case FLOAT_SYM:
printf("Type of number : FLOAT\n");
printf("Value of number : %f\n",yylval.yfloat);
break;
default:
printf("Type of number : UNDEFINED\n");
printf("Value of number : UNDEFINED\n");
break;
}
}
return(0);
}
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