C++ for Scientists - Technische Universität Dresden

44 CHAPTER 2. C++ BASICS
float divide (float a, float b){
return std::floor( a / b ) ;
}
int main (){
int x=5,y=2;
float n=5.0,m=2.0;
std::cout ≪ divide (x,y) ≪ std::endl;
std::cout ≪ divide (n,m) ≪ std::endl;
return 0;
} % ≫ ≫ ≫ ≫
In this case we have defined two functions with the same name, divide, but one of them accepts
two parameters of type int and the other one accepts them of type float. In the first call to
divide the two arguments passed are of type int, therefore, the function with the first prototype
is called. This function returns the result of dividing one parameter by the other. The second
call passes two arguments of type float, so the function with the second prototype is called.
This one executes a similar division and rounds the result.
2.6.5 Assertions
The function assert is a special kind of function and has the following interface:
void assert (int expression);
If the argument expression evaluates to 0, this causes an assertion failure that terminates the
program. A message is written to the standard error device and abort is called, terminating
the program execution.
The specifics of the message shown depend on the specific implementation in the compiler, but
it shall include: the expression whose assertion failed, the name of the source file, and the line
number where it happened. A usual expression format is:
Assertion failed: expression, file filename, line linenumber
This allows for a programmer to include many assert calls in a source code while debugging
the program. The many assert calls may reduce the performance of the code and so it would
be desirable to disable asserts for high-performance libraries. Asserts are disabled by including
the following line
#define NDEBUG
at the beginning of his code, before the inclusion of cassert or by defining the variable in the
compiler, e.g.
g++ -DNDEBUG foo.cpp
Example:
#include
#include
int main ()
{