Cannot convert type 'string' to 'float'

You need to do

float x = float.Parse(TextBox_item_price.Text);

try this:

float f; 
float.TryParse(TextBox_item_price.Text, out f);

use this:

float x = float.Parse(TextBox_item_price.Text);

use Float.TryParse. This will return true if parsing is successful. Else false will be returned. No exception is thrown.

Like this

float x;
if (float.TryParse(TextBox_item_price.Text, out x))
{
            //success
}

it wil work fine

float x=float.Parse(TextBox_item_price.Text);

You can not use type casting between incompatible types, use Single.TryParse or Convert.ToSingle

To convert between non-compatible types, such as integers and System.DateTime objects, or hexadecimal strings and byte arrays, you can use the System.BitConverter class, the System.Convert class, and the Parse methods of the built-in numeric types, such as Int32.Parse.

try this:

var a = string.Empty;
var b = float.Parse(a);

Try This:

(float)System.Convert.ToSingle(TextBox1.Text);

or this:

float.Parse(TextBox1.Text);

try this:

You can use float.Parse() instead of using float x=(float)(); it will works fine

try this;

Convert.ToDouble(TextBox_item_price.Text)

instead of;

(float)(TextBox_item_price.Text);