What does $ with a numeric value mean in Delphi

What does开发者_如何学C it means, in Delphi, when I see a command like this:

char($23)

What does the dollar symbol mean in this context?

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The dollar symbol represents that the following is a hex value.

ShowMessage(Char($23)); shows #.

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The $ symbol is used to prefix a hexadecimal literal. The documentation says:

Numerals

Integer and real constants can be represented in decimal notation as sequences of digits without commas or spaces, and prefixed with the + or - operator to indicate sign. Values default to positive (so that, for example, 67258 is equivalent to +67258) and must be within the range of the largest predefined real or integer type.

Numerals with decimal points or exponents denote reals, while other numerals denote integers. When the character E or e occurs within a real, it means "times ten to the power of". For example, 7E2 means 7 * 10^2, and 12.25e+6 and 12.25e6 both mean 12.25 * 10^6.

The dollar-sign prefix indicates a hexadecimal numeral, for example, $8F. Hexadecimal numbers without a preceding - unary operator are taken to be positive values. During an assignment, if a hexadecimal value lies outside the range of the receiving type an error is raised, except in the case of the Integer (32-bit integer) where a warning is raised. In this case, values exceeding the positive range for Integer are taken to be negative numbers in a manner consistent with two's complement integer representation.

So, in your example, $23 is the number whose hexadecimal representation is 23. That number has decimal representation 35, so you can write:

Assert($23 = 35);

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It represents a character. For example char(13) is end of line.