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使用Regex（POSIX）查找#ifdef语句外的printf（）调用

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我被同事要求提出一个正则表达式（POSIX语法）来查找 printf(...); 的调用 - 在一个c代码文件中 - 它不在 #ifdef ... #endif 范围内 .

然而，由于我只是在Uni学习Regex，我对此并不完全有信心 .

场景看起来像这样：

possibly some code
printf(some_parameters);  // This should match
possibly more code

#ifdef DEBUG
possibly some code
printf(some_parameters);  // This shouldn't match
possibly more code
#endif

possibly some code
printf(some_parameters);  // This should also match
possibly more code

请注意，c文件可能根本不包含#ifdef / #endif语句，在这种情况下，对 printf(); 的所有调用都应匹配 .

到目前为止我尝试过的是：

(?<!(#ifdef [A-Å0-9]+)).*printf\(.*\);.*(?!(#endif))

......以及围绕着* *的位置（甚至包含/排除） .

任何帮助或提示赞赏 .

c regex posix c-preprocessor

2 回答

  • 1

    不需要正则表达式 .

    cpp -D<your #define options here> | grep printf
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  • 0

    正则表达式不是解决此问题的好方法 . 它们不能很好地处理多行搜索，并且它们可以表达的模式受到限制，例如：使用regexen无法指定任意嵌套 .

    解决此问题的正确方法是使用旨在处理C代码中的条件编译指令的工具 . 这将是编译器的C预处理器，或者像 unifdef 这样的专用工具：

    $ unifdef -UDEBUG file.c | grep printf
printf(some_parameters);  // This should match
printf(some_parameters);  // This should also match

    从手册：

    UNIFDEF(1)                BSD General Commands Manual               UNIFDEF(1)

NAME
     unifdef, unifdefall — remove preprocessor conditionals from code

SYNOPSIS
     unifdef [-ceklst] [-Ipath -Dsym[=val] -Usym -iDsym[=val] -iUsym] ... [file]
     unifdefall [-Ipath] ... file

DESCRIPTION
     The unifdef utility selectively processes conditional cpp(1) directives.
     It removes from a file both the directives and any additional text that
     they specify should be removed, while otherwise leaving the file alone.

     The unifdef utility acts on #if, #ifdef, #ifndef, #elif, #else, and #endif
     lines, and it understands only the commonly-used subset of the expression
     syntax for #if and #elif lines.  It handles integer values of symbols
     defined on the command line, the defined() operator applied to symbols
     defined or undefined on the command line, the operators !, <, >, <=, >=,
     ==, !=, &&, ||, and parenthesized expressions.  Anything that it does not
     understand is passed through unharmed.  It only processes #ifdef and
     #ifndef directives if the symbol is specified on the command line, other‐
     wise they are also passed through unchanged.  By default, it ignores #if
     and #elif lines with constant expressions, or they may be processed by
     specifying the -k flag on the command line.
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