void killvar(list *head)
{
list *temp;
temp = findtable(head);
if (!temp)
return;
delvar(&temp->head, &temp->tail);
}
static int handledel() {
char *name = strtok(NULL,' ');
if (!name || strlen(name)==0)
return ERRNONAME;
return delvar(name);
}
/* exercise4-7 - Write a routine ungets(s) that will push back an entire
* string onto the input. Should ungets know about buf and bufp, or
* should it just use ungetch?
*
* exercise4-7_main.c - reverse Polish calculator */
int main()
{
int type;
double op1, op2;
double ans; /* most recently printed value */
char s[MAXOP];
int ispop; /* when 0, a value from the stack will not be popped upon newline */
int varindex; /* index of variable name and value for variable operations */
int i;
ispop = 1;
while ((type = getop(s)) != EOF)
{
switch (type)
{
case NUMBER:
push(atof(s));
break;
case ERROR:
printf("%s", s);
break;
case '+':
push(pop() + pop());
break;
case '*':
push(pop() * pop());
break;
case '-':
op2 = pop();
push(pop() - op2);
break;
case '/':
op2 = pop();
if (op2 != 0.0)
push(pop() / op2);
else
printf("error: zero divisor\n");
break;
case '%':
op2 = pop();
if (op2 != 0.0)
push((long) pop() % (long) op2);
else
printf("error: zero divisor\n");
break;
case '\n':
if (ispop == 0)
{
ispop = 1;
}
else
{
printf("\t%.8g\n", (ans = pop()));
}
break;
case SYMBOL:
/* stack commands */
if (strcmp(s, "print") == 0)
{
prnt();
ispop = 0;
}
else if (strcmp(s, "duplicate") == 0)
{
duplicate();
ispop = 0;
}
else if (strcmp(s, "swap") == 0)
{
swap();
ispop = 0;
}
else if (strcmp(s, "clear") == 0)
{
clear();
ispop = 0;
}
/* math commands */
else if (strcmp(s, "sin") == 0)
{
push(sin(pop()));
}
else if (strcmp(s, "cos") == 0)
{
push(cos(pop()));
}
else if (strcmp(s, "tan") == 0)
{
push(tan(pop()));
}
else if (strcmp(s, "exp") == 0)
{
push(exp(pop()));
}
else if (strcmp(s, "log") == 0)
{
push(log(pop()));
}
else if (strcmp(s, "pow") == 0)
{
op2 = pop();
op1 = pop();
if (op1 == 0.0 && op2 <= 0.0)
printf("error: base is 0 and exponent is 0 or less\n");
else if (op1 <= 0.0 && floor(op2) != op2)
printf("error: base is less than 0 and exponent is not an integer\n");
else
push(pow(op1, op2));
}
else if (strcmp(s, "ans") == 0)
{
push(ans);
}
/* set variable */
else if (strncmp(s, "assignto:", 9) == 0)
{
for (i = 0; s[i+9] != '\0'; i++)
s[i] = s[i+9];
s[i] = '\0';
if (strcmp(s, "") != 0)
setvar(s, pop());
else
printf("error: cannot assign variable with no variable name\n");
}
else if (strncmp(s, "delvar:", 7) == 0)
{
for (i = 0; s[i+7] != '\0'; i++)
s[i] = s[i+7];
s[i] = '\0';
delvar(s);
}
/* variable recall and default */
else
{
if ((varindex = getvarindex(s)) >= 0)
push(getvar(varindex));
else
printf("error: unknown symbol/command %s\n", s);
}
break;
default:
printf("error: unknown command %s\n", s);
break;
}
}
return 0;
}
