Question

Suppose you created a main() to deal with an exercise you asked your students.

Every student is supposed to write their own function, with the same API. And a single file will be created, with all functions and the main calling them.

Lets say: int studentname(int a, int b) is the function pattern.

One way I deal with it was using a vector of pointer to functions int (*func[MAX])(). But you need to fulfill the vector one by one func[0]=studentname;.

I wonder, is there a way a function can be called by its name somehow?

Something like: int student1(int a , int b), student2(), etc.

And in main somehow we could just call sscanf(funcname,"student%d",i); funcname();.

Do you have any other idea? Maybe

int studentname(int a, int b, char *fname)
{
    strcpy(fname, "studentname");

Anything creative will do! 🙂

Thanks!
Beco

PS. I tried just a vector of functions, but C won’t allow me! 🙂

int func[2]()={{;},{;}};

This way I could just give to each student a number, and voilá… But no way. It was funny though.

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Edited: I’m using linux.

Edited 2: Thanks! I’ve accepted an answer that helped me, but I’ve also documented a complete example as an answer bellow.

Answer 1

Maybe a bit overcomplicating it, but spontaneous idea:

• Compile all student source files into one shared library with the students’ functions being exports.
• Then enumerate all exposed functions, call and test them.

As an alternative:

• Write a small tool that will compile all “student units” using a preprocessor define to replace a predefined function name with an unique name (“func1”, “func2”, etc.).
• Then let the tool write a small unit calling all these functions while performing tests, etc.

And yet another idea:

• Use C++ to write a special class template that’s going to register derived classes in a object factory and just embed student’s code using extern "C". Depending on the implementation this might look a bit confusing and overcomplicated though.
• Then use the factory to create one instance of each and run the code.

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Example for the approach with dlopen() and dlsym() (whether only one function per library or all – doesn’t matter):

void *pluginlib = dlopen("student1.so", RTLD_NOW); // RTLD_NOW will load the file right away
if (!pluginlib)
    ; // failed to load
studentproc func = (studentproc)dlsym(pluginlib, "student1"); // this loads the function called "student1"
if (!func)
    ; // failed to resolve
func("hello world!"); // call the lib
dlclose(pluginlib); // unloads the dll (this will make all further calls invalid)