The following table describes the custom numeric format specifiers:
| Format Specifier | Name | Description |
|---|---|---|
| 0 | Zero placeholder | If the value being formatted has a digit in the position where the '0' appears in the format string, then that digit is copied to the output string. The position of the leftmost '0' before the decimal point and the rightmost '0' after the decimal point determines the range of digits that are always present in the output string. |
| # | Digit placeholder | If the value being formatted has a digit in the position where the '#' appears in the format string, then that digit is copied to the output string. Otherwise, nothing is stored in that position in the output string. Note that this specifier never displays the '0' character if it is not a significant digit, even if '0' is the only digit in the string. It will display the '0' character if it is a significant digit in the number being displayed. |
| . | Decimal point | The first '.' character in the format string determines the location of the decimal separator in the formatted value; any additional '.' characters are ignored. The actual character used as the decimal separator is determined by the NumberDecimalSeparator property of the NumberFormatInfo object that controls formatting. |
| , | Thousand separator and number scaling | The ',' character serves two purposes. First, if the format string contains a ',' character between two digit placeholders (0 or #) and to the left of the decimal point if one is present, then the output will have thousand separators inserted between each group of three digits to the left of the decimal separator. The actual character used as the decimal separator in the output string is determined by the NumberGroupSeparator property of the current NumberFormatInfo object that controls formatting. Second, if the format string contains one or more ',' characters immediately to the left of the decimal point, then the number will be divided by the number of ',' characters multiplied by 1000 before it is formatted. For example, the format string '0,,' will represent 100 million as simply 100. Use of the ',' character to indicate scaling does not include thousand separators in the formatted number. Thus, to scale a number by 1 million and insert thousand separators you would use the format string '#,##0,,'. |
| % | Percentage placeholder | The presence of a '%' character in a format string causes a number to be multiplied by 100 before it is formatted. The appropriate symbol is inserted in the number itself at the location where the '%' appears in the format string. The percent character used is dependent on the current NumberFormatInfo class. |
| E0 E+0 E-0 e0 e+0 e-0 | Scientific notation | If any of the strings 'E', 'E+', 'E-', 'e', 'e+', or 'e-' are present in the format string and are followed immediately by at least one '0' character, then the number is formatted using scientific notation with an 'E' or 'e' inserted between the number and the exponent. The number of '0' characters following the scientific notation indicator determines the minimum number of digits to output for the exponent. The 'E+' and 'e+' formats indicate that a sign character (plus or minus) should always precede the exponent. The 'E', 'E-', 'e', or 'e-' formats indicate that a sign character should only precede negative exponents. |
| 'ABC' "ABC" | Literal string | Characters enclosed in single or double quotes are copied to the output string literally, and do not affect formatting. |
| ; | Section separator | The ';' character is used to separate sections for positive, negative, and zero numbers in the format string. |
| True|False | Boolean format | String representation for two Boolean values, True and False separated with ‘|’, Strings "True" and "False" can be replaced with any other strings representing the two Boolean values. |
| Other | All other characters | All other characters are copied to the output string as literals in the position they appear. |
The following table displays examples using the custom numeric format specifiers:
| CustomFormat | Value | Output |
|---|---|---|
| ##### | 123 | 123 |
| 00000 | 123 | 00123 |
| (###) ### - #### | 1234567890 | (123) 456 – 7890 |
| #.## | 1.2 | 1.2 |
| 0.00 | 1.2 | 1.20 |
| 00.00 | 1.2 | 01.20 |
| #,# | 1234567890 | 1,234,567,890 |
| #,, | 1234567890 | 1235 |
| #,,, | 1234567890 | 1 |
| #,##0,, | 1234567890 | 1,235 |
| #0.##% | 0.086 | 8.6% |
| 0.###E+0 | 86000 | 8.6E+4 |
| 0.###E+000 | 86000 | 8.6E+004 |
| 0.###E-000 | 86000 | 8.6E004 |
| [##-##-##] | 123456 | [12-34-56] |
| ##;(##) | 1234 | 1234 |
| ##;(##) | -1234 | (1234) |
