Re: [Flex-help] Fwd: how to read input from a file in the scanner?

[Martin A. D. N. <mad...@gm...>]

Hi Pranay,

the declarations of x and y are fine. Give the following a shot (I added
yywrap as it wouldn't compile on my system otherwise -- I did not track
down why)

%{
	#include <stdio.h>
	int x=0,y=0;
%}

%%

\n   { ++x; ++y; printf("Found newline\n"); }
.    { ++y;  printf("Found something else\n"); }

%%

int main(void)
{
	yyin = fopen("input.txt", "r");
	yylex();
	printf("No. of lines is %d and no. of characters are %d\n", x, y);

	exit(EXIT_SUCCESS);
}

int yywrap (void){
	return 1;
}


Cheers, Martin

pranay agarwal wrote:
> hi, i am using lex for the first time , i am trying to take input from a
> file and not from the terminal , however i am facing problem please help
> here is my lex file :
> 
> 
> %{
> #include <stdio.h>
> int x=0,y=0;
> %}
> 
> %%
> '\n'   ++x,++y;
> '.'    ++y;
> %%
> main()
> {
> extern FILE * yyin;
> yyin= fopen("/home/username/example_test","r");
> yyrestart(yyin);
> printf("No. of lines is %d and no. of characters are %d\n",x,y);
> }
> 
> the name of this file is test.l and the name of the input file is
> example_test
> i tried the following in command line in linux:
> lex test.c
> cc lex.yy.c -o test -ll
> ./test
> 
> and the output is 0 for both x and y when it should be 2 and 20 respectively
> .
> 
> Is there a mistake in declaring the global variables x ,y?
> 
> 
> 

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Martin Alexander Neumann

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