Update Reader::fetchOne and Reader::fetchCol default values

README.md

@@ -228,10 +228,13 @@ $data = $reader->fetchAssoc(['firstname', 'lastname', 'email']);
 > * If the number of values in a CSV row is lesser than the number of named keys, the method will add `null` values to compensate for the missing values.
 > * If the number of values in a CSV row is greater that the number of named keys the exceeding values will be drop from the result set.
 
-#### fetchCol($columnIndex, $callable = null)
+#### fetchCol($columnIndex = 0, $callable = null)
 
 `fetchCol` returns a sequential array of all values in a given column from the CSV data.
 
+* If no argument is given to the method it will return the first colum from the CSV data.
+* If the column does not exists in the csv data the method will return an array full of null value.
+
 ```php
 $data = $reader->fetchCol(2);
 // will return something like this :
@@ -247,9 +250,9 @@ The methods listed above (`fetchAll`, `fetchAssoc`, `fetchCol`) can all take a o
 * the current csv key
 * the current csv Iterator Object
 
-#### fetchOne($offset)
+#### fetchOne($offset = 0)
 
-`fetchOne` return one single row from the CSV data. The required argument `$offset` represent the row index starting at 0.
+`fetchOne` return one single row from the CSV data. The required argument `$offset` represent the row index starting at 0. If no argument is given to the method it will return the first row from the CSV data.
 
 ```php
 $data = $reader->fetchOne(3); ///accessing the 4th row (indexing starts at 0)

src/Reader.php

@@ -102,7 +102,7 @@ public function query(callable $callable = null)
      *
      * @throws \InvalidArgumentException If the $offset is not a valid Integer
      */
-    public function fetchOne($offset)
+    public function fetchOne($offset = 0)
     {
         $this->setOffset($offset);
         $this->setLimit(1);
@@ -170,7 +170,7 @@ public function fetchAssoc(array $keys, callable $callable = null)
      *
      * @throws \InvalidArgumentException If the column index is not a positive integer or 0
      */
-    public function fetchCol($columnIndex, callable $callable = null)
+    public function fetchCol($columnIndex = 0, callable $callable = null)
     {
         if (false === filter_var($columnIndex, FILTER_VALIDATE_INT, ['options' => ['min_range' => 0]])) {
             throw new InvalidArgumentException(