void print_postfix(struct node *root)
{
if (root == NULL)
return;
print_postfix(root->left);
print_postfix(root->right);
printf("%s ", root->token);
}
void infix_to_postfix(char *postfix, const char *infix) {
stack_t stack;
int i, j, len, p;
char topstack, c;
char str[2];
char msg[64];
len = strlen(infix);
stack_init(&stack);
j = 0;
str[1] = 0;
for (i = 0; i < len; i++) {
c = infix[i];
switch (c) {
case ' ':
case '\t':
case '\n':
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
case '.':
print_postfix(c, j);
break;
case '(':
str[0] = c;
stack_push(&stack, str);
break;
case ')':
while (c != '(') {
c = stack_pop(&stack, NULL);
if (c != '(') {
print_postfix(' ', j);
print_postfix(c, j);
}
}
break;
case '+':
case '-':
case '*':
case '/':
print_postfix(' ', j);
topstack = stack_top(&stack, NULL);
p = check_precedence(topstack, c);
while (p && !stack_empty(&stack)) {
print_postfix(stack_pop(&stack, NULL), j);
print_postfix(' ', j);
topstack = stack_top(&stack, NULL);
p = check_precedence(topstack, c);
}
str[0] = c;
stack_push(&stack, str);
break;
default:
sprintf(msg, "invalid char %c", c);
fatal(msg);
}
}
while (!stack_empty(&stack)) {
print_postfix(' ', j);
print_postfix(stack_pop(&stack, NULL), j);
}
print_postfix(0, j);
}
