5.10

1 files changed, 59 insertions, 0 deletions

diff --git a/5/10.c b/5/10.c
new file mode 100644
index 0000000..febd4c1
--- /dev/null
+++ b/5/10.c
@@ -0,0 +1,59 @@
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define MAXLEN 1000
+
+int main(int argc, char *argv[]) {
+  char op[MAXLEN], *s; 
+  int val[MAXLEN], i, j, k, op1, op2;
+
+  if (argc == 1) {
+    printf("Usage: expr 2 3 4 + *\n");
+    return 1;
+  }
+  
+  for(i = 0, j = 0, ++argv; --argc > 0 && i < MAXLEN - 1 && j < MAXLEN - 1; argv++) {
+    s = *argv;
+    if (isdigit(*s))
+      val[i++] = atoi(s);
+    else if (s[0] == '+' || s[0] == '-' || s[0] == '*' || s[0] == '/' || s[0] == '%')
+      op[j++] = s[0];
+    else {
+      printf("error: %s not supported\n", s);
+      return -1;
+    }
+  }
+
+  k = j;
+  j = 0;
+  
+  while (j < k && i > 1) {
+    op2 = val[--i];
+    op1 = val[--i];
+    switch (op[j++]) {
+    case '+':
+      val[++i] = op1 + op2; 
+      break;
+    case '-':
+      val[++i] = op1 - op2; 
+      break;
+    case '*':
+      val[++i] = op1 * op2; 
+      break;
+    case '/':
+      val[++i] = op1 / op2; 
+      break;
+    case '%':
+      val[++i] = op1 % op2; 
+      break;
+    default:
+      printf("error: unkknown op\n");
+      return 1;
+    }
+  }
+
+  printf("\t%d\n", val[0]);
+
+  return 0;
+}