lex入門

sample.lex

%{
    enum {
        INT = 1,
        FLOAT,
        ID,
        NUM,
        REAL,
        COMMA,
        EQ,
        EX,
        QU,
        SEMI,
        ADD,
        SUB,
        MUL,
        DIV,
        LPAR,
        RPAR,
        ERROR
    };
%}

%%

int                         {return INT;}
float                       {return FLOAT;}
[a-z][a-z0-9]*              {return ID;}
0|[1-9][0-9]*               {return NUM;}
([0-9]+"."[0-9]*)|([0-9]*"."[0-9]+)  {return REAL;}
","                         {return COMMA;}
"="                         {return EQ;}
"!"                         {return EX;}
"?"                         {return QU;}
";"                         {return SEMI;}
"+"                         {return ADD;}
"-"                         {return SUB;}
"*"                         {return MUL;}
"/"                         {return DIV;}
"("                         {return LPAR;}
")"                         {return RPAR;}
"\n"|" "|"\t"               { }
"/*"[a-z0-9 ]*"*/"          { }
.                           {return ERROR;}

%%

int yywrap(void){ return 1;}
int main(void){
    int t;
    while((t=yylex()) != 0){
        printf("number = %d, string = '%s'\n", t, yytext);
    }
}

('-')/ Compiler flex sample.lex 1:55:55
('-')/ Compiler cc lex.yy.c 1:55:56
('-')/ Compiler ./a.out 1:55:58
ab = .2/**/
number = 3, string = 'ab'
number = 7, string = '='
number = 5, string = '.2'