how can I remove zeros from exponent notation

Question

I'm using exponential formatting to format a decimal number in C#. For example if the number is

0.0001234567

Formatting with

(0.0000123456).ToString("E4");

Shows

1.2345E-004

How can I remove leading zero from exponent so it read as below?

1.2345E-4

Answer 1

Assuming you need to always show 4 digits after decimal point, try

"0.0000E+0"

so it will show

(0.0000123456).ToString("0.0000E+0"); //1.2345E-5 
(0.0000120000).ToString("0.#E+0");    //1.2000E-5

if you don't need to show 4 digits after decimal points use

"0.#E+0"

so it will show

(0.0000123456).ToString("0.#E+0"); //1.2E-5
(0.0000120000).ToString("0.#E+0"); //1.2E-5

Answer 2

Quoting MSDN:

The case of the format specifier indicates whether to prefix the exponent with an "E" or an "e". The exponent always consists of a plus or minus sign and a minimum of three digits. The exponent is padded with zeros to meet this minimum, if required.

This is with the standard number specifier.

However, with the custom number format, you can set the number of 0's:

987654 ("#0.0e0") -> 98.8e4

For your case, it's

(0.0000123456).ToString("#0.0E0"); //12.3E-6

Edit after BobSort comment

If you need scientific notation, you can specify that you need only one digit before decimal with the following:

(0.0000123456).ToString("0.00#E0"); //1.23E-5