4.2

1 files changed, 20 insertions, 1 deletions

diff --git a/4/2.c b/4/2.c
index 0f842e8..2f94001 100644
--- a/4/2.c
+++ b/4/2.c
@@ -22,7 +22,7 @@ int main(int argc, char *argv[]) {
 }
 
 double atof(char s[]) {
-  int i, sign;
+  int i, j, sign, exp, exp_sign;
   double val, power;
 
   for (i = 0; isspace(s[i]); i++)
@@ -44,5 +44,24 @@ double atof(char s[]) {
     power *= 10.0;
   }
 
+  if (s[i] == 'e' || s[i] == 'E')
+    i++;
+
+  exp_sign = s[i] == '-' ? -1 : 1;
+
+  for (i++, exp = 0; isdigit(s[i]); i++)
+    exp = 10 * exp + (s[i] - '0');
+  
+  if (exp_sign < 0)
+    exp = exp_sign * exp;
+
+  if (exp < 0) {
+    for (j = exp; j < 0; j++)
+      power *= 10.0;
+  } else {
+    for (j = 0; j < exp; j++)
+      power /= 10.0;
+  }
+
   return sign * val / power;
 }
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