Github Link

https://github.com/rusuraluca/lftc/tree/main/lftc_lab8

Docs

lang.lxi

%{
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int currentLine = 1;
%}

%option noyywrap

identifier      [a-zA-Z~][a-zA-Z0-9]*
integer         0|[+|-]?[1-9][0-9]*
char            [\\'][a-zA-z0-9][\\']
string          [\\"][a-zA-z0-9]*[\\"]

%%

"program"|"list"|"int"|"char"|"string"|"while"|"for"|"var"|"START"|"END"|"if"|"else"|"write"|"in"|"finish"    {printf("Reserved word: %s\\n", yytext);}
"+"|"-"|"*"|"/"|"%"|"="|"!"|"!="|"=="|"+="|"-="|"/="|"*="|"<"|">"|">="|"<="|"||"|"&&"		                {printf("Operator: %s\\n", yytext);}
"["|"]"|"{"|"}"|"("|")"|","|";"|"'"|"\\""                                                                    {printf("Separator: %s\\n", yytext);}
{identifier}		                                                                                        {printf("Identifier: %s\\n", yytext);}
{integer}		                                                                                            {printf("Number: %s\\n", yytext);}
{char}		                                                                                                {printf("String: %s\\n", yytext);}
{string}		                                                                                            {printf("Character: %s\\n", yytext);}

[ \\t]+		{}
[\\n]+	{currentLine++;}

[0-9][a-zA-Z0-9]*	   {printf("Illegal identifier at line %d\\n", currentLine);}
".+"                   {printf(".+ is not a recognised operator");}

%%

void main(argc, argv)
int argc;
char** argv;
{
if (argc > 1)
{
    FILE *file;
    file = fopen(argv[1], "r");
    if (!file)
    {
        fprintf(stderr, "Could not open %s\\n", argv[1]);
        exit(1);
    }
    yyin = file;
}

yylex();
}

How to run:

flex lang.lxi
gcc -o run lex.yy.c
./run < inputs/p1.txt
./run < inputs/p2.txt
./run < inputs/p3.txt
./run < inputs/perr.txt