Counting functions in C source code

Question

I have complete project in C, which can be built with gcc or Visual Studio. There are no calls to external libraries.

I would like to know how many functions there

Answer 1

i have an idea to count the functions .c file.. wecan count this .java file also. this is c# class file and you can pass the file to the the class

class CountFunctions
{

    private FileInfo File;
    private int functions = 0;

    public int getNumberOfFunctions
    {
        get { return functions; }
    }

    public countfunctions(FileInfo fs) {
        File = fs;
        getLineOfCode();
    }

    private void getLineOfCode()
    {
        string line;
        try
        {
            StreamReader reader = File1.OpenText();
            while (true)
            {
                line = reader.ReadLine();

                if (IsFunction(line))
                {
                    Functions++;
                }

                if (line == null)
                    break;
            }
        }
        catch (Exception r)
        {
            Console.WriteLine(r.Message);
        }

    }

    private bool IsFunction(string line)
    {
        if (line.Contains("void") || line.Contains("int") || line.Contains("short") || line.Contains("long") || line.Contains("float") || line.Contains("char") || line.Contains("double"))
        {
            if (!line.Contains(";"))
            {
                return true;
            }
        }
        return false;
    }
} 

Answer 2

The definition of functions might be not as simple as you believe. In particular, functions in the C source code do not match functions in the generated assembly code, notably because of inlined functions.

^{The number and size of functions depend upon the optimization level and the compiler.}

And many headers (e.g. <stdio.h>) could contain inline functions. If they are not called, the compiler probably would optimize by not emitting their code (and same could be true with some static functions). Quite often, functions declared static inline do not appear in the optimized code.

Likewise, some macros might get expanded into some function definitions....

If compiling with a sufficiently recent version of GCC (e.g. 4.7 or newer) you might make a simple MELT extension for that purpose. The biggest advantage is that it works inside GCC so will really count what GCC is doing... (e.g. after some optimizations).

Notice that GCC might generate or remove some functions during optimizations (function cloning, function inlining....)

^{GCC MELT is obsolete since 2017}

Answer 3

Frama-C has a metrics plug-in that among other things computes the number of functions in your program. Just use

frama-c -metrics file1.c file2.c ... filen.c

to get as output something like:

          Global metrics
      ============== 
      Sloc = 2080
      Decision point = 117
      Global variables = 51
      If = 117
      Loop = 22
      Goto = 75
      Assignment = 613
      Exit point = 242
      Function = 841
      Function call = 871
      Pointer dereferencing = 447

Answer 4

You can also use ctags and parse the tag file. A quick way would be to do something like :

ctags -R -f - . | grep -w f | wc -l

at the root directory of your project but this might not be always correct, for instance if you have a global variable like this somewhere in your tree:

int f;   

Answer 5

With gcc:

$ nm elf_file | grep "T " | grep -v " _" | wc -l

Note that gcc can inline some functions even with optimizations disabled, so you should compile with:

-O0 -fno-builtin -fno-inline-functions-called-once

(-finline-functions-called-once is enabled by default even in -O0)

Answer 6

A tool for static analysis of C source code is Edison Design Group. It is the compiler front end and you can leverage it to calculate all sort of metrics for your code.