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POLex - recognizing tokens
 

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  1. POLex - recognizing tokens
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    <p>I am trying to learn Lex. I have a simple program where i want to read in a file and recognize tokens.</p> <p>Right now i am getting some errors. I think i am having problems because there is more than one line in the file to recognize the tokens?</p> <p>Here is the file</p> <pre><code>fd 3x00 bk setc 100 int xy3 fd 10 rt 90 </code></pre> <p>here is the output i am trying to achieve:</p> <pre><code>Keyword: fd Illegal: 3x00 Keyword: bk Keyword: setc Number: 100 Keyword: int </code></pre> <p>here is my program:</p> <pre><code>%{ /* Comment */ #include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; %} %% fd {printf("Keyword: fd\n");} [0-9][a-z][0-9] {printf("Illegal: 3x00\n");} bk {printf("Keyword: bk\n");} setc[0-9] {printf("Keyword: setc\n Number: %s\n", yytext);} int {printf("Keyword: int\n");} xy3 {printf("ID: xy3\n");} fd[0-9] {printf("Keyword: fd\n Number %s\n", yytext);} rt[0-9] {printf("Keyword: rt \n Number %s\n", yytext);} %% main( argc, argv) int argc; char** argv; { if(argc &gt; 1) { FILE *file; file = fopen(argv[1], "r"); if(!file) { fprintf(stderr, "Could not open %s \n", argv[1]); exit(1); } yyin = file; } yylex(); } </code></pre> <p>here are the errors i am getting when i try to compile it:</p> <pre><code> In function 'yylex': miniStarLogo.l:11: error: expected expression before '[' token miniStarLogo.l:11: error: 'a' undeclared (first use in this function) miniStarLogo.l:11: error: (Each undeclared identifier is reported only once miniStarLogo.l:11: error: for each function it appears in.) miniStarLogo.l:11: error: expected ';' before '{' token miniStarLogo.l:13: error: expected expression before '[' token miniStarLogo.l:13: error: expected ';' before '{' token </code></pre> <p>is the error in my printf statements? Thank you</p>
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    1. COThat looks like a compiler error, are you having trouble compiling or running it? It compiles and runs for me, though the output isn't quite what you want.
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      1. USKevin
    2. COthats the error i get when i try to compile it. I tried cc lex.yy.c -o myprog -ll
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    3. COHow were you able to compile and run it? What command did you use?
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