正则表达式查找某个函数的所有调用，而不是其声明

Question

I need to write a regex which will match only lines with the C function call, not its declaration.

So, I need it to match only lines, where funcName() is not preceeded by int , double , float , char etc. and an arbitrary number of spaces.

---

The problem is, I can run into following expressions:

printf("Hello"); int f() {return 1;};

So I must consider even the situation, where there are some other characters before the date-type name.

myStruct f();

In this situation I want regex to match it, ONLY basic data-types should be excluded.

---

So far I've got to this expression:

^(?!(void|int|double|char))\s*f\(\).*$

But I have no idea, how to take care of the situation with characters before the type name.

Answer 1

The following regex meets your specs:

(^|((^|\s)(?!(void|int|double|char))[^\s]+)\s+)([a-zA-Z_]+\(\)?)

• The function name is defined by a character class containing letters and the underscore.
• The line starts with the function call, or
• the line contains at least one non-whitespace character before the function name. In that case ...
  • this non-WS sequence does not match the excluded keywords
  • there is at least 1 WS character before the function name

See the live demo at regex101 .

Caveat

As several commentors have noted, this is not a robust solution . It will work for a tightly constrained set of function call and declaration patterns only.

A general regex-based solution (if possible at all, which would heavily depend on the regex engine features available) will be of theoretical interest only as it had to mimic completely the C preprocessor.