1. Assume the following text is presented to a C scanner:

main(){

const float payment = 384.00;

float bal;

int month = 0;

bal=15000;

while (bal>0){

printf("Month: %2d Balance: %10.2f ", month, bal);

bal=bal-payment+0.015*bal;

month=month+1;

}

}

Programming: Use Lex to produce a lexical analyzer. You can use the regular definitions and actions in the page 143 of our text book. You have to include all tests, make files, etc.

What token sequence is produced? For which tokens must extra information be returned in addition to the token code?

3.5. THE LEXICAL-ANALYZER GENERATOR LEX 143 %{ /* definitions of manifest constants LT, LE, EQ, NE, GT, GE, IF, THEN, ELSE, ID, NUMBER, RELOP */ %} /* regular definitions */ delim [ \t ] WS {delim)+ letter [A-Za-z] digit [0-9] id {letter} ({letter}|{digit})* number {digit}+(\.{digit}+)?(E[+-]?{digit }+)? %% {ws) {/* no action and no return */} if {return(IF);} then {return(THEN);} else {return(ELSE);} {id} {yylval = (int) installID(); return(ID);} {number} {yylval = (int) installNum(); return (NUMBER); } {yylval = LT; return(RELOP); } {yylval = LE; return(RELOP); } " {yylval = EQ; return(RELOP); } {yylval = NE; return(RELOP); } > {yylval = GT; return(RELOP); } {yylval = GE; return(RELOP); } %% int installID () {/* function to install the lexeme, whose first character is pointed to by yytext, and whose length is yyleng, into the symbol table and return a pointer thereto */ } int installNum) {/* similar to installID, but puts numer- ical constants into a separate table */ } Figure 3.23: Lex program for the tokens of Fig. 3.12