Question

a) Name 5 different “data types” used in C++ programming.

b) Give an example of the kind of data that would be kept in each of the types listed in question (a).

c) What does it mean to pass a variable by “reference” rather than by “value?”

d) When would the above be useful to do?

e) What does the following code do?

int val;

cout << “Enter a value for processing: ”;

cin >> val;

cout << val < 0 ? -val : val;

f) What is the second line of the above code segment used for?

Answer 1

Answer a.) 5 different data types used in c++ are :

Integer, Floating point, Boolean, Character, Void or valueless (int, float, bool, char, void)

Answer b.)

int - any integer like 0, 1, -10, 298

float- any number having decimal point as well like 2.00 , 289.003

bool- “true” or “false”

char- any character value example alphabets ‘a’ , ‘m’, ‘z’... any special symbol like ‘&’ , ‘@‘

void- means without a value, used for functions which do not return anything.

Answer c.) Let’s understand both by examples

Say I have a function :

void incByOne (int a){

a=a+1;

}

int main(){

int x=2;

incByOne(x);

cout<<x; //will print 2 since value of x is not changed by function incByOne as the value was passed to it as ‘pass by value’

return 0;

}

now if we have same function but the arguments are passed as a reference like below

void incByOne (int &a){

a=a+1;

}

int main(){

int x=2;

incByOne(x);

cout<<x; //will print 3 now since value of x is changed by function incByOne as the value was passed to it as ‘pass by reference’

}

Answer d.) When we don’t want the function to make its own argument copies and act on them , and instead we want to use our own passed arguments inside the function doing all the calculations on them directly we can use pass by reference .

Answer e.) The program asks the user to enter an integer value

If the entered value is less than zero, it prints the same negative number as in number with a minus sign

if the entered value is greater than or equal to zero, the same number is printed on console .

Answer f.) the second line prompts on the console “Enter a value for processing” ,

prompting the user to enter a value on the input device