Question

我的同事要求我提出一个正则表达式（POSIX语法）来查找printf(...);的调用 - 在c代码文件中 - 不在{ {1}} ... #ifdef范围。

然而，由于我只是在Uni学习Regex，我对它并不完全有信心。

场景看起来像这样：

#endif

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

到目前为止我尝试过的是：

printf();

......以及。*

的位置（甚至包含/排除）

任何帮助或提示表示赞赏。

Answer 1

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.

Answer 2

不需要正则表达式。

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

使用Regex（POSIX）查找#ifdef语句外的printf（）调用

2 个答案: