No iostream for makefile compilation but fine with regular compilation-CodePudding

I have a file like this: (p1.c)

  1 #include <iostream>                                                                                                
  5
  6 int main(int argc, char* argv[]) {
  7    std::cout << "No iostream\n";
  8    return 0;
  9 }

And I try to compile with a simple makefile like this:

  1 app: p1.o                                                                                                          
  2     g   p1.o -o p1
  3
  4 clean:
  5     rm *.o p1 p2

Running make yields this:

p1.c:1:10: fatal error: iostream: No such file or directory
 #include <iostream>
          ^~~~~~~~~~
compilation terminated.
<builtin>: recipe for target 'p1.o' failed
make: *** [p1.o] Error 1

But running g p1.c works fine, no issues.

Am I doing something wrong in the make file? I've had no other troubles with libraries besides iostream.

CodePudding user response：

You have only specified a Makefile rule to link the object file to an executable. You haven't actually specified a rule to compile the source code file to an object file.

Therefore make will try to use an implicit rule to build the object file p1.o from p1.c.

Because p1.c has the file ending .c it will assume that the file is C source code and call cc to compile it, which should be a C compiler, not a C compiler.

In C there is no <iostream> and so the compilation fails.

Change the file name from p1.c to p1.cpp or p1.cxx or p1.cc or some of the other conventional file endings for C . It is not only confusing to make, but also confusing to other programmers, when a .c file doesn't actually contain C source code.