main.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <ctype.h>
   5
   6 #include "expression.h"
   7 #include "expressionbase.h"
   8
   9 #define MAX 4096
  10
  11 int main(int argc, char* argv[]) {
  12     int i = 0, factor = 1;
  13     unsigned char next;
  14     char expression[MAX];
  15     ExpressionBase *base = new_expression_base();
  16     Expression *expr = malloc(sizeof(Expression)), *prevp;
  17
  18
  19     while(next = getchar()) {
  20         if(next == '\n') { // We hit end of line, make last expression and break
  21             if (get_value(expression)) { // We don't have an empty expression
  22                 finish_expression(expr, expression, next, factor);
  23                 add_tail(base, expr);
  24             }
  25             break;
  26         }
  27
  28         if(isdigit(next) || next == '.') { // We hit a number - add that to the stack
  29             if (i == 0 && base->last && base->last->op == 0) { // after (
  30                 base->last->op = '*';
  31             }
  32             expression[i] = next;
  33             ++i;
  34         } else if ( next == '*' || next == '/' || next == '+' || next == '-' || next == '^') { // We hit an operator, make a new expression
  35             if (i == 0) { // after (
  36                 base->last->op = next;
  37                 continue;
  38             }
  39             finish_expression(expr, expression, next, factor);
  40             add_tail(base, expr);
  41
  42             expr = malloc(sizeof(Expression));
  43             strncpy(expression, "\0", strlen(expression));
  44             i = 0;
  45         } else if (next == '(') {
  46             if (get_value(expression)) {
  47                 finish_expression(expr, expression, '*', factor);
  48                 add_tail(base, expr);
  49             }
  50             expr = malloc(sizeof(Expression));
  51             strncpy(expression, "\0", strlen(expression));
  52             i = 0;
  53             factor *= 10;
  54         } else if (next == ')') {
  55             finish_expression(expr, expression, 0, factor);
  56             add_tail(base, expr);
  57
  58             expr = malloc(sizeof(Expression));
  59             strncpy(expression, "\0", strlen(expression));
  60             i=0;
  61             factor /= 10;
  62         } else { // We didn't hit a digit or an operator - do nothing
  63             continue;
  64         }
  65     }
  66
  67     for (expr = base->first; expr; expr = expr->next) {
  68         evaluate(expr);
  69         prevp = expr;
  70     }
  71     printf("= %.1f\n", prevp->value);
  72     return 0;
  73 }
  74