diff --git a/README.md b/README.md
index 552f5b7..29cd9bb 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ If a value can not be converted you should return the following *falsy* value fo
 
 There are a few special cases:
 
-1. If an `array` is passed as *input* to `convert_to_string()`, it should a string representation of the elements, in order, as a comma separated list. For example, an input of `[1, 2, 3]` should return `1, 2, 3`, an input of `[1]` should return `1`.
+1. If an `array` is passed as *input* to `convert_to_string()`, it should be a string representation of the elements, in order, as a comma separated list. For example, an input of `[1, 2, 3]` should return `1, 2, 3`, an input of `[1]` should return `1`.
 2. If any of the *falsy* values above or the string `null` is passed as *input* to `convert_to_null()`, it should return `null`. Otherwise, it should return the original *input*.
 
 ## Just getting started?
diff --git a/src/data_types.php b/src/data_types.php
new file mode 100644
index 0000000..068c3bc
--- /dev/null
+++ b/src/data_types.php
@@ -0,0 +1,48 @@
+<?php 
+
+function convert_to_int($input) {
+	return (int)$input;
+}
+
+function convert_to_float($input) {
+	settype($input, "float");
+	if(is_float($input)) {
+		return $input;
+	} else {
+		return 0.0;
+	}
+}
+
+function convert_to_string($input) {
+	if(is_array($input)) {
+		return implode(", ", $input);
+	} else {
+	return (string)$input;
+	}
+}
+	
+function convert_to_bool($input) {
+	settype($input, "bool");
+	if(is_bool($input)) {
+		return $input;
+	} else {
+		return false;
+	}
+}
+
+function convert_to_array($input) {
+	settype($input, "array");
+	if(is_array($input)) {
+		return $input;
+	} else {
+		return [];
+	}
+}
+
+function convert_to_null($input) {
+	if(!$input || $input === "null") {
+		return null;
+	} else {
+		return $input;
+	}
+}