#line
The #line directive allows you to define arbitrary line numbers for the source lines. Normally, the compiler counts lines starting at line number 1; using the #line directive, you can specify an arbitrary line number at any point. The compiler then uses that line number for subsequent counts.
Example
#include <stdio.h>
main()
{
printf("A\n"); //A
#line100 //H
printf("B\n"); //B
printf("C FILE %s LINE %d\n", __FILE__, __LINE__ );//C
#line200 //K
printf("D\n"); //D
printf("E\n"); //E
}
Explanation
- The statement H indicates the #line directive.
- The #line number in statement B is taken as 100 and for statement C, it is taken as 101.
- The #line number in statement D is taken as 200 and for statement E, it is taken as 201.
- If you introduce any error in statement B then the compiler will display the error at #line number 100.
- C has provided two special identifiers: __FILE__ and __LINE__, which indicate the file name of the source file and the current line number, respectively.
Point to Remember
- #line is used to indicate line numbers which can be used for debugging.
