Some functions for their implementation don't need arguments – that functions have empty list of arguments (inside the brackets father the name of the function). For example function main (in Visual Studio the function main have arguments but in general for example DevC++ generally doesn't). So for the structure of function main in the Dev C++ has the following form
int main( )
Functions without arguments are usually used for printing messages or for printing data whose result depends exclusively on code inside of same function.