Print debugging statement: Difference between revisions

=={{header|Delphi}}==

{{libheader| winapi.windows}}

{{libheader| System.sysutils}}

Delphi has a "OutputDebugString" for debug, but not give lines and filename of source.

<lang Delphi>

program DebugApp;

{$APPTYPE CONSOLE}

uses

winapi.windows,

System.sysutils;

function Add(x, y: Integer): Integer;

begin

Result := x + y;

OutputDebugString(PChar(format('%d + %d = %d', [x, y, result])));

end;

begin

writeln(Add(2, 7));

readln;

end.</lang>

In next we have a workaround using a idea from '''user3989283'''[[https://stackoverflow.com/questions/7214213/how-to-get-line-number-at-runtime]]. This code override the default assert function to gain access to line and file name.

Obs.: In this example default action of assert is disabled, but you can enable calling in HookAssert (at end).

<lang Delphi>

program DebugApp;

{$APPTYPE CONSOLE}

uses

winapi.windows,

System.sysutils,

System.ioutils;

var

OldAssert: TAssertErrorProc;

procedure HookAssert(const M, F: string; L: Integer; E: Pointer);

var

msg: string;

fFile: Text;

const

LOG_FILE = '.\Debug.log';

begin

msg := '[' + DateTimeToStr(now) + ']';

msg := msg + format(' [Line: %.4d] File: %s', [L, F]);

Assign(fFile, LOG_FILE);

if FileExists(LOG_FILE) then

Append(fFile)

else

Rewrite(fFile);

Write(fFile, msg + #10);

Write(fFile, M + #10);

Close(fFile);

// Uncomment next line to enable the original assert function

// OldAssert(M, F, L, E);

end;

procedure AttachDebug;

begin

OldAssert := AssertErrorProc;

AssertErrorProc := HookAssert;

end;

procedure ReleaseDebug;

begin

AssertErrorProc := OldAssert;

end;

function Add(x, y: Integer): Integer;

begin

Result := x + y;

Assert(false, (format('%d + %d = %d', [x, y, result])));

end;

begin

AttachDebug;

writeln(Add(2, 7));

ReleaseDebug;

end.</lang>

{{out}}

Example log:

<pre>

[26/08/2020 18:56:51] [Line: 0051] File: ...\Debug\DebugApp.dpr

2 + 7 = 9

</pre>