Code from 4.4.1 added and run once

main.c

@@ -122,7 +122,8 @@ void getNonBlank() {
 		getChar();
 }
 
-/*****************************************************/
+/
+*****************************************************/
 /* lex - a simple lexical analyzer for arithmetic
 expressions */
 int lex() {
@@ -169,3 +170,69 @@ int lex() {
 	printf("Next token is: %d, Next lexeme is %s\n", nextToken, lexeme);
 	return nextToken;
 } /* End of function lex */
+
+/* expr
+	Parses strings in the language generated by the rule:
+	<expr> -> <term> {(+ | -) <term>}
+*/
+void expr() {
+	printf("Enter <expr>\n");
+/* Parse the first term */
+	term();
+/* As long as the next token is + or -, get
+the next token and parse the next term */
+	while (nextToken == ADD_OP || nextToken == SUB_OP) {
+		lex();
+		term();
+	}
+	printf("Exit <expr>\n");
+} /* End of function expr */
+
+/* term
+	Parses strings in the language generated by the rule:
+	<term> -> <factor> {(* | /) <factor>)
+*/
+void term() {
+	printf("Enter <term>\n");
+/* Parse the first factor */
+	factor();
+/* As long as the next token is * or /, get the
+	next token and parse the next factor */
+	while (nextToken == MULT_OP || nextToken == DIV_OP) {
+		lex();
+		factor();
+	}
+	printf("Exit <term>\n");
+} /* End of function term */
+
+/* factor
+	Parses strings in the language generated by the rule:
+	<factor> -> id | int_constant | ( <expr )
+*/
+void factor() {
+	printf("Enter <factor>\n");
+/* Determine which RHS */
+	if (nextToken == IDENT || nextToken == INT_LIT)
+/* Get the next token */
+		lex();
+/* If the RHS is ( <expr>), call lex to pass over the
+	left parenthesis, call expr, and check for the right
+	parenthesis */
+	else {
+		if (nextToken == LEFT_PAREN) {
+			lex();
+			expr();
+			if (nextToken == RIGHT_PAREN)
+				lex();
+			else
+				error();
+		} /* End of if (nextToken == ... */
+
+/* It was not an id, an integer literal, or a left
+	parenthesis */
+	else
+		error();
+	} /* End of else */
+
+printf("Exit <factor>\n");;
+} /* End of function factor */