#@title Writing Lex program
%%writefile program.l

%{
    #include <stdio.h>
    int ctChar=0;
    int ctSpace=0;
    int ctWord=0;
    int ctLine=0;
%}
WORD [^ \t\n,\.:]+
EOL [\n]
BLANK [ ]
%%

{WORD} {ctWord++; ctChar+=yyleng;}
{BLANK} {ctSpace++;}
{EOL} {ctLine++;}
. {ctChar++;}
%%

void main(int argc, char *argv[]){
    if(argc!=2){
        printf("Usage:\n\t./a.out <FILENAME>\n");
        exit(0);
    }

    yyin=fopen(argv[1],"r");
    yylex();

    printf("Word Count: %d\n",ctWord);
    printf("Character Count: %d\n",ctChar);
    printf("Space Count: %d\n",ctSpace);
    printf("Line Count: %d\n",ctLine);
    fclose(yyin);

}

int yywrap(){
    return 1;
}

Standard output is empty

ERROR: /home/zFZVC4/prog:5:5: Syntax error: Operator expected
ERROR: /home/zFZVC4/prog:41:0: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Can't ignore goal at this port
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Can't ignore goal at this port
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Can't ignore goal at this port
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Can't ignore goal at this port
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: No previous search
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? ERROR: Unknown option (h for help)
   Exception: (3) program ? ERROR: Can't ignore goal at this port
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ?    Exception: (3) program ?