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// FILE: useful.h
// PROVIDES: A toolkit of useful functions for random numbers and displays.
// Note that these are in the global namespace.
//
// FUNCTIONS in the toolkit:
// double random_fraction( )
// Postcondition: The return value is a random real number in the closed
// interval [0..1] (including the endpoints).
//
// double random_real(double low, double high)
// Precondition: low <= high.
// Postcondition: The return value is a random real number in the closed
// interval [low..high] (including the endpoints).
//
// void display(double x)
// Postcondition: The function has written one line of output to the
// standard ouput, with a vertical bar in the middle. If x is positive,
// then approximately x stars are printed to the right of the vertical
// bar. If x is negative, then approximately -x stars are printed to the
// left of the vertical bar. If the absolute value of x is more than
// 39, then only 39 stars are printed.
// Examples:
// display(8) prints: |********
// display(-4) prints: ****|
//
// void eat_line( )
// Postcondition: Up to next newline has been read and discarded from cin.
//
// bool inquire(const char query[ ])
// Precondition: query is a null-terminated string of characters.
// Postcondition: query has been printed, and a one-line response read
// from the user. The function returns true if the user's response begins
// with 'Y' or 'y', and returns false if the user's response begins with
// 'N' or 'n'. (If the response begins with some other letter, then the
// query is repeated.)
#ifndef USEFUL_H // Prevent duplicate definition
#define USEFUL_H
double random_fraction( );
double random_real(double low, double high);
void display(double x);
void eat_line( );
bool inquire(const char query[ ]);
#endif
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