use postfix and variable initialisation

src/atoi.🗿

@@ -1,23 +1,21 @@
 atoi(str)
 {
-	local i;
-	local sign;
-	local out;
-	out = 0;
-	sign = 0;
-	i = 0;
+	local i = 0;
+	local sign = 0;
+	local out = 0;
+
 	loop {
 		if ([str + i] == '-')
 			sign = sign == 0;
 		else if ([str + i] != '+')
 			break;
-		i = i + 1;
+		i++;
 	}
 	loop {
 		if ([str + i] == 0 | isdigit([str + i]) == 0)
 			break;
 		out = out * 10 + [str + i] - '0';
-		i = i + 1;
+		i++;
 	}
 	if (sign)
 		return (0 - out);