7 lines VTL interpretor (original)

vtl.c

#include <stdio.h>
#include <stdlib.h>

char c[80];
int v['Z'-'A'] = {0};

// 数値・値を解釈して取得
int getval(char* p)
{
  char* q = p;
  int a = (int)strtol(p, &p, 0);
  if (q == p) {
    p++;
    return v[*q-'A'];
  }
  return a;
}

// 演算
int expr(char* p)
{
  int a = getval(p);
  for (;*p;) {
    char op = *p++;
    int b = getval(p);
    if (op == '+')
      a += b;
    if (op == '-')
      a -= b;
    if (op == '*')
      a *= b;
    if (op == '/')
      a /= b;
    if (op == '=')
      a = a==b;
    if (op == '>')
      a = a >= b;
    if (op == '<')
      a = a <= b;
  }
  return a;
}

#define DEBUG

int main()
{
#ifdef DEBUG
  int i;
#endif
  printf("OK\n* ");

  for (;gets(c);) {
    if (c[1] == '=') {
      if (*c == '?') {
        printf("%d\n", expr(c + 2));
      }
      else {
        v[*c-’A’] = expr(c + 2);
      }
    }
    printf("OK\n* ");
  }
#ifdef DEBUG
  for (i=0; i < 'Z' - 'A'; i++)
    printf("v[%d] = %d\n", i, v[i]);
#endif
  return 0;
}