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$\%\{$

#include

#include

int line$\_$num $=1$; $//$ Track the current line number

int char$\_$pos $=1$; $//$ Track the character position on the line

$\%\}$

$\%$option noyywrap

DIGIT $[0-9]$

LETTER $[$A$-$Za$-$z$]$

SYMBOL $[\_$@$\backslash .]$

ID $\{$LETTER$\}(\{$LETTER$\}|\{$DIGIT$\})*(\{$SYMBOL$\})*(\{$LETTER$\}|\{$DIGIT$\})*$

NUM $\{$DIGIT$\}+|\{$DIGIT$\}+"."\{$DIGIT$\}+(($E$|$e$)(\backslash +|-)?\{$DIGIT$\}+)?$

$\%\%$

$\{$DIGIT$\}+\backslash .\{$DIGIT$\}*[$Ee$][^0-9]\{$

fprintf$($stderr$,$ "Error: Incomplete token at line $\%$d$,$ position $\%$d

$",$ line$\_$num, char$\_$pos$)$;

char$\_$pos $+=$ yyleng;

$\}$

$\{$DIGIT$\}+\backslash .\{$DIGIT$\}*[$Ee$][\backslash +\backslash -]?[^0-9]\{$

fprintf$($stderr$,$ "Error: Incomplete token at line $\%$d$,$ position $\%$d

$",$ line$\_$num, char$\_$pos$)$;

char$\_$pos $+=$ yyleng;

$\}$

$\{$ID$\}+[!$#$$\%^$&$*\backslash (\backslash )\backslash -\backslash +\backslash =\backslash [\backslash ]\backslash \{\backslash \}\backslash \text{'}\backslash "$;:~$]\{$

fprintf$($stderr$,$ "Error: Invalid character in identifier at line $\%$d$,$ position $\%$d

$",$ line$\_$num, char$\_$pos$)$;

char$\_$pos $+=$ yyleng;

$\}$

$[!$#$$\%^$&$*\backslash (\backslash )\backslash -\backslash +\backslash =\backslash [\backslash ]\backslash \{\backslash \}\backslash \text{'}\backslash "$;:~$\_$@$]\{$ID$\}\{$

fprintf$($stderr$,$ "Error: Symbol at beginning of identifier at line $\%$d$,$ position $\%$d

$",$ line$\_$num, char$\_$pos$)$;

char$\_$pos $+=$ yyleng;

$\}$

$\{$ID$\}\{$printf$("$Token: ID$,$ Lexeme: $\%$s at line $\%$d$,$ position $\%$d

$",$ yytext, line$\_$num, char$\_$pos$)$;$\}$

$\{$NUM$\}\{$printf$("$Token: NUM, Lexeme: $\%$s at line $\%$d$,$ position $\%$d

$",$ yytext, line$\_$num, char$\_$pos$)$;$\}$

$"/*"([^*]|(\backslash *+[^*/]))*"*/"\{$char$\_$pos $+=$ yyleng;$\}$

$"/*"([^*]|(\backslash *+[^*/]))*\{$fprintf$($stderr$,$ "Error: Unclosed comment at line $\%$d$,$ position $\%$d

$",$ line$\_$num, char$\_$pos$)$;exit$(1)$;$\}$

$\{$line$\_$num$++$;char$\_$pos $=1$;$\}$

$[\backslash$t$]+\{$char$\_$pos $+=$ yyleng;$\}$

$.\{$fprintf$($stderr$,$ "Error: Unknown character $\text{'}\%$s$\text{'}$ at line $\%$d$,$ position $\%$d

$",$ yytext, line$\_$num, char$\_$pos$)$;$\}$

$\%\%$

int main$($void$)\{$

yylex$()$;

return $0$;

$\}$