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| author | Fuwn <[email protected]> | 2024-04-07 23:18:32 -0700 |
|---|---|---|
| committer | Fuwn <[email protected]> | 2024-04-07 23:18:32 -0700 |
| commit | c1b6ffe70bd281c6c230fd63fabcaac2aff47514 (patch) | |
| tree | e8af3b1782a7cd0754590ed618fddc1bdb9b7385 /appendix | |
| download | dscode-c1b6ffe70bd281c6c230fd63fabcaac2aff47514.tar.xz dscode-c1b6ffe70bd281c6c230fd63fabcaac2aff47514.zip | |
Diffstat (limited to 'appendix')
| -rw-r--r-- | appendix/useful.cxx | 80 | ||||
| -rw-r--r-- | appendix/useful.h | 45 |
2 files changed, 125 insertions, 0 deletions
diff --git a/appendix/useful.cxx b/appendix/useful.cxx new file mode 100644 index 0000000..79dff57 --- /dev/null +++ b/appendix/useful.cxx @@ -0,0 +1,80 @@ +// FILE: useful.cxx
+// IMPLEMENTS: A toolkit of functions (See useful.h for documentation.)
+
+#include <assert.h> // Provides assert
+#include <ctype.h> // Provides toupper
+#include <iostream.h> // Provides cout, cin, get
+#include <stdlib.h> // Provides rand, RAND_MAX
+#include "useful.h"
+
+void display(double x)
+// Library facilities used: iostream.h, stdlib.h
+{
+ const char STAR = '*';
+ const char BLANK = ' ';
+ const char VERTICAL_BAR = '|';
+ const int LIMIT = 39;
+ int i;
+
+ if (x < -LIMIT)
+ x = -LIMIT;
+ else if (x > LIMIT)
+ x = LIMIT;
+
+ for (i = -LIMIT; i < 0; i++)
+ {
+ if (i >= x)
+ cout << STAR;
+ else
+ cout << BLANK;
+ }
+ cout << VERTICAL_BAR;
+ for (i = 1; i <= LIMIT; i++)
+ {
+ if (i <= x)
+ cout << STAR;
+ else
+ cout << BLANK;
+ }
+ cout << endl;
+}
+
+double random_fraction( )
+// Library facilities used: stdlib.h
+{
+ return rand( ) / double(RAND_MAX);
+}
+
+double random_real(double low, double high)
+// Library facilities used: assert.h
+{
+ assert(low <= high);
+ return low + random_fraction( ) * (high - low);
+}
+
+void eat_line( )
+// Library facilities used: iostream.h
+//
+{
+ char next;
+
+ do
+ cin.get(next);
+ while (next != '\n');
+}
+
+bool inquire(const char query[ ])
+// Library facilities used: ctype.h, iostream.h
+{
+ char answer;
+ do
+ {
+ cout << query << " [Yes or No]" << endl;
+ cin >> answer;
+ answer = toupper(answer);
+ eat_line( );
+ }
+ while ((answer != 'Y') && (answer != 'N'));
+ return (answer == 'Y');
+}
+
diff --git a/appendix/useful.h b/appendix/useful.h new file mode 100644 index 0000000..4513936 --- /dev/null +++ b/appendix/useful.h @@ -0,0 +1,45 @@ +// FILE: useful.h
+// PROVIDES: A toolkit of useful functions for random numbers and displays.
+//
+// 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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