__LINE__ The line number in the current source file. The line number is a decimal integer constant. It can be altered with a #line directive. The #line Directive The #line directive tells the preprocessor to change the compiler’s internally stored line number and filename to a given line number and filename. The compiler uses the line number and filename to refer to errors that it finds during compilation. The line number usually refers to the current input line, and the filename refers to the current input file. The line number is incremented after each line is processed.Syntax#linedigit-sequence "filename"optThe digit-sequence value can be any integer constant. Macro replacement can be performed on the preprocessing tokens, but the result must evaluate to the correct syntax. The filename can be any combination of characters and must be enclosed in double quotation s (" "). If filename is omitted, the previous filename remains unchanged.You can alter the source line number and filename by writing a #line directive. The translator uses the line number and filename to determine the values of the predefined macros __FILE__ and __LINE__. You can use these macros to insert self-descriptive error messages into the program text.
The #line directive tells the preprocessor to change the compiler’s internally stored line number and filename to a given line number and filename. The compiler uses the line number and filename to refer to errors that it finds during compilation. The line number usually refers to the current input line, and the filename refers to the current input file. The line number is incremented after each line is processed.Syntax#linedigit-sequence "filename"optThe digit-sequence value can be any integer constant. Macro replacement can be performed on the preprocessing tokens, but the result must evaluate to the correct syntax. The filename can be any combination of characters and must be enclosed in double quotation s (" "). If filename is omitted, the previous filename remains unchanged.You can alter the source line number and filename by writing a #line directive. The translator uses the line number and filename to determine the values of the predefined macros __FILE__ and __LINE__. You can use these macros to insert self-descriptive error messages into the program text.