added print variables command

k&r/04-funcs-and-prog-struct/04-calc.c

@@ -5,6 +5,7 @@
 #include <ctype.h> 
 #include <assert.h>
 
+
 /* --------- ERROR MESSAGES */
 #define printerr(format, ...) printf("error: " format "\n", ##__VA_ARGS__)
 #define ZERODIV_ERR "zero divisor"
@@ -16,6 +17,7 @@
 #define UNKNOWN_TOKEN_ERR "unknown token %s"
 #define VAR_NOT_SET_ERR "variable %c has no value"
 
+
 /* --------- PROMPT FORMATS */
 #define PROMPT_F     ">> "
 #define POP_PRINT_F  "pop -> %.8g\n"
@@ -25,6 +27,7 @@
     "Type 'help' for a list of available commands\n" \
     PROMPT_F
 
+
 /* ------ GLOBAL VALUE STACK */
 #define MAXVAL 100 /* maximum depth of val stack */
 
@@ -51,6 +54,7 @@ double val[MAXVAL];
         } \
    } while (0) 
 
+
 /* -------- STACK PRINTING FUNCTIONS */
 double lst_print;
 /* print_peek: print top element, leave stack unchanged */
@@ -58,16 +62,20 @@ double lst_print;
 /* print_pop: pop top element and print it */
 #define print_pop() printf(POP_PRINT_F, lst_print = pop())
 
+
 /* ------- GLOBAL VARIABLE NAMESPACE */
 #define NS_SIZE ('z' - 'a' + 1)
     
 char var_flags[NS_SIZE];
 double var_vals[NS_SIZE];
 
+/* is_var: return 0 if c is not a variable name */
+#define is_var(c) isalpha(c)
+
 /* set_var: pop val from stack, set variable c to val */
 #define set_var(c) \
     do { \
-        int i = c - 'a'; \
+        int i = tolower(c) - 'a'; \
         var_flags[i] = 1; \
         var_vals[i] = pop(); \
     } while (0)
@@ -75,17 +83,26 @@ double var_vals[NS_SIZE];
 /* get_var: push value of c to stack */
 #define get_var(c) \
     do { \
-        int i = c - 'a'; \
+        int i = tolower(c) - 'a'; \
         if (!var_flags[i]) \
             printerr(VAR_NOT_SET_ERR, i+'a'); \
         else \
             push(var_vals[i]); \
     } while (0)
 
+/* print_vars: print all set variables and their values */
+void print_vars(void)
+{
+    int i;
+    for (i = 0; i < NS_SIZE; i++)
+        if (var_flags[i])
+            printf("%c = %.8g\n", i+'a', var_vals[i]);
+}
 
 /* --------- CALCULATOR FUNCTION TYPES */
+/* the following macros allow us to call native c constructs 
+ * in a declarative style */
 
-/* the following macros allow us to call native c constructs in a declarative style */
 /* value */
 #define VALUE(ID) push(ID)
 /* command */
@@ -115,12 +132,9 @@ double var_vals[NS_SIZE];
 
 
 /* --------- CALCULATOR FUNCTIONS */
-
 /* renaming macro */
 #define CALL(TOKEN, F, APPLY, ...) APPLY(F, ##__VA_ARGS__)
 
-void help(void);
-
 #define COMMANDS \
     X(_, "last printed value", CALL, lst_print, VALUE) \
     X(ENTER, "pop top of stack and print it", CALL, print_pop, COMMAND) \
@@ -129,6 +143,7 @@ void help(void);
     X(swap, "swap top two elements of stack", COMMAND) \
     X(clear, "clear stack", COMMAND) \
     X(help, "print all available commands", COMMAND) \
+    X(vars, "print defined variables and their values", CALL, print_vars, COMMAND)
 
 #define OPERATORS \
     X(+, "add operands", COMM_OP) \
@@ -163,7 +178,6 @@ void help(void);
     X(min, "minimum value", CALL, fmin, COMM_FUN) \
     X(pi, "value of pi", CALL, M_PI, VALUE)
     
-
 #define TOKENS \
     COMMANDS \
     OPERATORS \
@@ -176,11 +190,10 @@ void help(void);
 
 
 /* --------- MAIN PROGRAM */ 
-
 #define MAXTOKEN 100
 int gettoken(char *token, int max_t);
 char * parsef(char *s, double *x);
-
+void help(void);
 
 /* reverse Polish calculator */
 int main()
@@ -203,8 +216,8 @@ int main()
         TOKENS
     #undef X
     #define X(C, DESC, F) \
-        if (t_len == 2 && token[0] == C && isalpha(token[1])) \
-            F(tolower(token[1])); \
+        if (t_len == 2 && token[0] == C && is_var(token[1])) \
+            F(token[1]); \
         else
         VAR_TOKENS
     #undef X
@@ -213,14 +226,15 @@ int main()
         else
             printerr(UNKNOWN_TOKEN_ERR, token);
     }
-    if (!length())
-        putchar('\n');
+
+    putchar('\n');
     while (length())
-        printf(POP_PRINT_F, pop());
+        print_pop();
 
     return 0;
 }
 
+
 /* ---------- HELP COMMAND */
 #define MAX_CMD_W 10 /* token padding */
 #define VAR_STR "X"  /* string to represent variable */
@@ -245,6 +259,7 @@ void help(void)
 #undef X
 }
 
+
 /* -------- PARSING FUNCTIONS */
 #define BLANK ' '
 
@@ -252,7 +267,6 @@ void help(void)
  * return token length, -1 on newline and 0 on EOF */
 int gettoken(char *token, int t_max) 
 {
-
     static int c = BLANK;
     
     while (isspace(c) && c != '\n') /* remove leading whitespace */
@@ -272,12 +286,10 @@ int gettoken(char *token, int t_max)
     return i;
 }
 
-/* ---------- CUSTOM ATOF */
 #define DEC_SEP X('.') X(',')
 #define EXP_SEP X('e') X('E')
 
-
-/* macros for parsef*/
+/* macros for parsef */
 #define SIGN(s) \
     ((*s == '-') ? (s++, -1) : ((*s == '+') ? (s++, 1) : 1))
 #define ATOI(s, x, ...) \