Correct type to not truncate info or raise errors

rust/src/p0008.rs

@@ -62,8 +62,8 @@ pub fn p0008() -> u64 {
     for i in 0..(string.len() - 13) {
         let slice = &string[i..(i + 13)];
         let mut prod: u64 = 1;
-        for c in slice.chars() {
-            prod *= (c - '0') as u64;
+        for c in slice.bytes() {
+            prod *= (c as u32 - '0' as u32) as u64;
         }
         if prod > answer {
             answer = prod;