ASSERT

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgAssert
• Last revised: 2023-07-09

---

Debugging macro that halts program execution if an expression is evaluated to 0 (false).

Syntax

` #define ASSERT(expression) if (expression) = 0 then : fb_Assert( FILE, LINE, FUNCTION, #expression ) : end if

`

Usage

` ASSERT( expression )

`

Parameters

expression

Any valid conditional/numeric expression. If expression evaluates to 0 (i.e. "false"), execution is halted.

Description

The ASSERT macro is intended for use in debugging and works only if the -g or -eassertoption is specified on thefbccommand line. In this case it prints an error message and stops the program execution ifexpressionevaluates to0

.

Its normal use is to check the correct value of the variables or expressions during debugging.

If

-g and -eassert are not passed to fbc, the macro does not generate any code, and has no effect.

Note: If an ASSERT fails while the program is in a graphics Screen (Graphics), the error message will not be visible as it will be printed to the graphics screen, which will be closed immediately after.

Examples

start GeSHi

Sub foo
 Dim a As Integer
 a=0
 Assert(a=1)
End Sub

foo

'' If -g or -eassert is used, this code stops with: test.bas(3): assertion failed at FOO: a=1

end GeSHi

Dialect Differences

• Not available in the -lang qb dialect unless referenced with the alias __ASSERT.

Differences from QB

• New to FreeBASIC

See also

• #assert
• ASSERTWARN
• Compiler Option: -eassert
• Compiler Option: -g

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