Boolean values are those which have a value of true or false. (cf. “4.1. Data types” and “Boolean operators and comparison operators”.) One of the operations we can perform on booleans is negation: that which is not true is false and that which is not false is true; in other words, the negation of true is false and the negation of false is true.
Write a program that reads several boolean values and prints their negation.
Input will consist of several lines containing either
For each line of input,
there should be a line of output with
the negation of the corresponding input value:
The submitted program should contain a
that receives one boolean as argument and returns a boolean.
Please refer to the information for the chosen language:
int negation(int p);
negation :: Bool -> Bool
bool negation(bool p);(see hint below)
public static bool Negation(bool p)in a public class
public static boolean negation(boolean p)in a public class
function negation (p)
Comparing strings to arrive at a bool. You can use string equality to create a boolean value from strings.
In Python and Haskell,
you can compare strings
s2 using the equality operator:
s1 == s2
This operator also works with literal strings:
str == "hello"
In C, you can compare strings using the
strcmp(s1, s2) == 0
When the result of
strcmp is 0 that means the given strings are equal.
strcmp function also works with literal strings:
strcmp(str, "hello") == 0
What are booleans? Read both “4.1. Data types” and “Boolean operators and comparison operators” sections of the Computer Science by Example book for an explanation of what are booleans and how to use them in programming.
Beware of the data types.
Users of Python and dinamically-typed languages beware.
negation function will be tested
with proper boolean values as its argument
and not with booleans encoded in strings.
This is similar to how the
of earlier exercises
do take proper integer values
and not integer values encoded as strings.
there is a distinction between the boolean value
and the string
Confusingly enough, in Python
'False' has a boolean value of
>>> bool('False') True
This comes from the fact that in Python,
boolean conversion from strings defaults to treating
empty strings as
False-valued and non-empty strings as
This similar to the distinction between
12 and the string
C++ namespace conflicts.
If you are facing namespace conflicts locally, read on.
Starting with C++17,
std namespace does export a name called
In this exercise,
you should avoid
using namespace std;
and import required
std symbols one by one:
using std::cin; using std::cout;
Or, you can simply prefix all uses with
try next: bool-and-or
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