PRB: NMAKE Does Not Parse Escape Character Correctly

• Microsoft NMAKE for MS-DOS, versions 1.11, 1.12, 1.13, 1.2, 1.3, and 1.4
• Microsoft NMAKE for OS/2, versions 1.11, 1.12, 1.13, and 1.21
• Microsoft NMAKE Utility for Windows NT, version 1.40

SYMPTOMS

In NMAKE, the caret (^) symbol is used as an escape character for the characters #()$^\{}!@- (which NMAKE uses as control characters). If you create an NMAKE macro that contains one of these symbols, you may, due to context, need to use the caret symbol to indicate that you want the literal character in the macro.

MORE INFORMATION

Using ^^ or ^$ gives unexpected results. In some cases, the leading caret is not removed even though it is needed to get a caret or dollar sign. However, NMAKE might also remove both characters. According to the Visual C/C++ for MS-DOS, version 1.0, README.WRI file, if you want to use $ in a command, then you need to use $$ instead of ^$. The README.WRI file also notes that if you want to use ^ as a literal character, it is treated as a literal character when used within a quoted string.

For example, if you create a macro containing two carets preceded by another character, such as abc^^abc, NMAKE will not parse out the first caret, leaving only one caret. Instead, it leaves both carets in the macro. If, on the other hand, you create a macro containing two carets preceded only by the equal sign for the macro assignment, such as ^^abc, NMAKE will parse out both carets leaving only the abc.

The sample makefiles below illustrate these situations. Each makefile contains comments showing the expected output and the actual output.

These sample makefiles all give the expected output with NMAKE 1.5 from Visual C++ 2.0.

Sample Makefile #1

Note: This makefile does work correctly for NMAKE for MS-DOS, versions 1.3 and later.

test=abc^!abc   # note: test=abc!abc works
ALL:
  echo $(test)

Sample Makefile #2

test=abc^$abc   # note: test=abc$$abc works
ALL:
  echo $(test)

Sample Makefile #3

test=abc^^abc ALL:

  echo $(test)

Since the ^ is treated as a literal character within a quoted string, you can place the macro definition in a string and then use macro substitution to remove the quotes. For example,

test="abc^abc" ALL:

  @echo $(test:"= )