Standard Predefined Macros - Revision history

Proj user18 at 10:23, 18 December 2016

2016-12-18T10:23:10Z

Proj user18 at 07:37, 18 December 2016

2016-12-18T07:37:01Z

Proj user18 at 07:31, 18 December 2016

2016-12-18T07:31:35Z

Proj user18 at 06:19, 18 December 2016

2016-12-18T06:19:54Z

Proj user18: Created page with "= Standard Predefined Macros = C exposes a plethora of predefined macros which can be very useful in our day-to-day coding. Also, we do encounter a few simple interview ques..."

2016-12-18T06:01:11Z

Created page with "= Standard Predefined Macros = C exposes a plethora of predefined macros which can be very useful in our day-to-day coding. Also, we do encounter a few simple interview ques..."

New page

= Standard Predefined Macros =

C exposes a plethora of predefined macros which can be very useful in our day-to-day coding.

Also, we do encounter a few simple interview questions along these lines.

Most common ones are along this line: How can we print the line number of a program or the file name.

Following are few of the macros and how they can be used:

=== __LINE__ ===
This macro expands to the current executing line number.

=== __FILE__ ===
This macro expands to the name of the current executing file.

=== __func__ ===
This macro expands to the name of the current executing function.

The above macros can be used as a part of debugging any errors in a particular part of the program.

<syntaxhighlight lang="c">
#include <iostream>

using namespace std;

void test_standard_predefined_macros();

int main()
{
test_standard_predefined_macros();

return 0;
}

void test_standard_predefined_macros()
{
cout << "File: " << __FILE__ << endl;
cout << "Function: " << __func__ << endl;
cout << "Line: " << __LINE__ << endl;
}

Output:
File: ../testPredefinedMacros.cpp
Function: test_standard_predefined_macros
Line: 18
</syntaxhighlight>

@@ Line 5: / Line 5: @@
 Also, we do encounter a few simple interview questions along these lines.
-Most common ones are: How can we print the line number of a program or the file name.
+Most common ones are: How do we print the line number in a program or the file name?
-Following are few of the macros and how they can be used:
+Following are few of the macros and a demonstration of how they can be used:
 === __LINE__ ===

← Older revision		Revision as of 07:31, 18 December 2016
Line 19:		Line 19:

	The above macros can be used as a part of debugging any errors in a particular part of the program.		The above macros can be used as a part of debugging any errors in a particular part of the program.
		+	It eliminates the need to write multiple debug messages. Also, it eliminates the problem of keeping any debug prints updated as code is modified.

	<syntaxhighlight lang="c">		<syntaxhighlight lang="c">

@@ Line 10: / Line 10: @@
 === __LINE__ ===
-This macro expands to the current executing line number.
+This macro expands to an integer value that specifies the current executing line number.
 === __FILE__ ===
-This macro expands to the name of the current executing file.
+This macro expands to a string constant that specifies the name of the current executing file.
 === __func__ ===
-This macro expands to the name of the current executing function.
+This macro expands to a string constant that specifies the name of the current executing function.
 The above macros can be used as a part of debugging any errors in a particular part of the program.
@@ Line 48: / Line 48: @@
 Line: 18
 </syntaxhighlight>