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//============================================================================
// Author : Sven Gothel
// Copyright : 2022 Gothel Software e.K.
// License : MIT
// Description : C++ Lesson 0.1 Functions
//============================================================================
#include <iostream>
#include <cassert>
/**
* Lesson 0.1 Functions
*
* This lesson demonstrates
* - function declaration and definition in same or different modules
*/
/**
* Function declaration with function name `add`.
*
* No program code is given.
*
* A function declaration is used to let the compiler
* know how to use a function.
*
* @param x int paramter 1
* @param y int paramter 2
* @return type int
*/
int add(const int x, const int y);
/**
* Function definition with function name `add`
* and given program code.
*
* A function definition must match a given function declaration, if exists.
*
* A function definition may be called if invoked.
*
* @param x int paramter 1
* @param y int paramter 2
* @return type int
*/
int add(const int x, const int y) {
return x + y;
}
// Include header file, which contains declaration of function `double_value` as defined in module lesson03_module.cpp.
// Linker has to link lesson01_function.o + lesson03_module.o to resolve this function!
#include "cpp_basics/lesson01_module.hpp"
int main(int argc, const char* argv[]) {
// A loop to print all program invocation arguments
{
for(int i=0; i<argc; ++i) {
std::cout << "cmd_arg[" << std::to_string(i) << "]: " << argv[i] << std::endl;
}
}
int error_counter = 0;
// invoke local function `add`
{
const int res = add(1, 2);
if( 3 != res ) {
++error_counter;
}
}
// invoke external function `double_value`
{
const int res = double_value(1);
if( 2 != res ) {
++error_counter;
}
}
// Demonstrate using address of a function, i.e. a function-pointer.
{
// `add_func` is a created type definition of a function
typedef int(*add_func)(const int, const int);
printf("10: add: address %p\n", add);
add_func f1 = add;
const int i = 10;
const int j = 20;
const int r = f1(i, j);
printf("11: i: %d, j %d: f1 %p, size f1 %zu, r %d\n", i, j, f1, sizeof(f1), r);
assert( add == f1 );
assert( i + j == r );
assert( 10 == i );
assert( 20 == j );
// Leaving this scope destructs all automatic allocated resources of this block: `f1`, `i`, `r`.
}
if( 0 == error_counter ) {
std::cout << "No error" << std::endl;
return 0;
} else {
std::cout << error_counter << " error(s)" << std::endl;
return 1;
}
}
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