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1.15. C and C++

Now for the most famous program of all time! This program is often the first program someone will write in a new language. Here it is presented in the original C language!

#include <stdio.h> int main() { printf("Hello World!"); }

You can also have C++ code in an activecode.

#include <iostream> using namespace std; int main() { cout << "Hello World!" << endl; cout << "Welcome to C++ Programming" << endl; }

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.. activecode:: lc2
   :language: cpp
   :stdin: 100
   :compileargs: ['-std=c++11', '-Wall', '-Wpedantic']

   #include <iostream>
   using namespace std;
   int main() {
       cout << "Hello World!" << endl;   cout << "Welcome to C++ Programming" << endl;
   }

1.16. Unit Tests in C++

You can also have hidden unit tests in C++ using catch.hpp. Place the unit tests after ‘====’.

Write a function to compute the factorial of a. number

unsigned int Factorial( unsigned int number ) { return number <= 1 ? number : Factorial(number-1)*number; } ==== #define CATCH_CONFIG_MAIN // This tells Catch to provide a main() - only do this in one cpp file #include <catch.hpp> TEST_CASE( "Factorials are computed", "[factorial]" ) { REQUIRE( Factorial(1) == 1 ); REQUIRE( Factorial(2) == 2 ); REQUIRE( Factorial(3) == 6 ); REQUIRE( Factorial(10) == 3628800 ); } TEST_CASE( "Factorial of 0", "[fact0]" ) { REQUIRE( Factorial(0) == 1); }

.. activecode:: cpp_units
    :language: cpp
    :autograde: unittest

    Write a function to compute the factorial of a. number
    ~~~~
    unsigned int Factorial( unsigned int number ) {
        return number <= 1 ? number : Factorial(number-1)*number;
    }

    ====

    #define CATCH_CONFIG_MAIN // This tells Catch to provide a main() - only do   this in one cpp file
    #include <catch.hpp>

    TEST_CASE( "Factorials are computed", "[factorial]" ) {
    REQUIRE( Factorial(1) == 1 );
    REQUIRE( Factorial(2) == 2 );
    REQUIRE( Factorial(3) == 6 );
    REQUIRE( Factorial(10) == 3628800 );
    }

    TEST_CASE( "Factorial of 0", "[fact0]" ) {
    REQUIRE( Factorial(0) == 1);
    }

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