# M2 Constants (Debugging with GDB)

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#### 15.4.9.3 Constants

GDB allows you to express the constants of Modula-2 in the following ways:

- Integer constants are simply a sequence of digits. When used in an expression, a constant is interpreted to be type-compatible with the rest of the expression. Hexadecimal integers are specified by a trailing ‘
`H`

’, and octal integers by a trailing ‘`B`

’. - Floating point constants appear as a sequence of digits, followed by a decimal point and another sequence of digits. An optional exponent can then be specified, in the form ‘
`E[+|-]nnn`

’, where ‘`[+|-]nnn`

’ is the desired exponent. All of the digits of the floating point constant must be valid decimal (base 10) digits. - Character constants consist of a single character enclosed by a pair of like quotes, either single (
`'`

) or double (`"`

). They may also be expressed by their ordinal value (their ASCII value, usually) followed by a ‘`C`

’. - String constants consist of a sequence of characters enclosed by a pair of like quotes, either single (
`'`

) or double (`"`

). Escape sequences in the style of C are also allowed. See C and C++ Constants, for a brief explanation of escape sequences. - Enumerated constants consist of an enumerated identifier.
- Boolean constants consist of the identifiers
`TRUE`

and`FALSE`

. - Pointer constants consist of integral values only.
- Set constants are not yet supported.