C++ Part 27

Rand Function

The C++ library with header file <cstdlib> contains a random number function
named rand. Rand function is making a Random number; however, the output is not completely random and mix the output with time function to receive a complete random number.

For example to make a random number between 0 to 10 (less than 10 ) you can use this method:

int i; for (i = 0; i < 10; i++) cout << rand( ) << endl;

A sequence of pseudorandom numbers is usually determined by one number known
as the seed.
Example 2 :

For this example I seed the srand with a number 99 . It can be any number , but usually mixing srand function with a current time will help to find a better random number.

int i; srand(99); for (i = 0; i < 10; i++) cout << (rand( ) % 11) << endl; srand(99); for (i = 0; i < 10; i++) cout << (rand( ) % 11) << endl;

C++ Part 25

Functions

• Breaks code down into manageable chunks to write (and divide across development team)
• Easier to debug – only one idea behind each module
• Easier to maintain – buggy modules may be replaced without worrying about ramifications on other modules
• Outsiders only need to know a module’s interface, not the details of its implementation.
• Avoids duplication of code ⇒ more compact, and also easier to modify if code has bug  

• Predefined functions: e.g., String.length(): String → Int  
• Programmer-Defined functions: used similarly to predefined functions  
  
  This predefined functions need using namespace std;
  

Source : Absolute C++