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It reads a character and convert it into upper case. 

eg: 

Enter an alphabet: a 

The output is A.

If a computer has no cctype header file the code is as follows, 

char ch;

cout<<“Enter an alphabet”;

cin>>ch;

if (ch >>= 97 && ch<<122)

cout<<ch – 32;

(a) call by value

Recursive function

The output is 0! = 120 

Because the address of variable ’a’ is given to the variable ‘n’ of the function fact(call by reference method). So the function changes its value (i.e. n-) to 0. Hence the result. To get the desired result call the function as call by value method in this method the copy of the value of the variable ‘a’ is given to the function. So the actual value of ‘a’ will not changed. 

So instead of int fact(int &n) just write int fact(int n), i.e., no need of & symbol.

A function calls itself is known as recursion.

#include<iostream>

using namespace std; 

int fac(int); 

int main() 

{ 

int n; 

cout<<“enter a number”;

cin>>n;

cout<<fac(n); 

} 

int fac(int n) 

{

if (n == 1) return (1); 

else 

return (n × fac(n – 1)); 

}

The working of this program is as follows If the value of n is 5 then it calls the function as fa. The function returns value 5 × fac(4), That means this function calls the function again and returns 5 ×4 × fac(3). This process continues until the value n = 1. So the result is 5 × 4 × 3 × 2 × 1 = 120.

(b) n = sum(10,20)

The process of converting big programs into smaller programs is known as modularisation. This small programs are called modules or sub programs or functions. C++ supports modularity in programming called functions. 

C++ function return One Value 

Here the function is declared with one optional argument. So the function call with minimum one argument is compulsory.

1. It is valid. Here a becomes 2 and b becomes 3. 

2. It is also valid . Here a becomes 2 and b takes the default value 2. 

3. It is not a valid call. One argument is compulsory.

In the case of a sub function a return statement helps to terminate the sub function and return back to the main function or called function. But in the case of a main function it terminates the program.

There is an error. The error is ‘r’ is a constant V must be initialised and cannot be changed during execution.

A number is said to be perfect square is the factors of the number are in pair

We have given numbers

(i) 725 = 5×5×29

As the factors of 725 are not in pair so it is not a perfect square

(ii) 190 = 2×5×19

Factor of 190 are not in pair so it is not a perfect square

(iii) 841 = 29 ×29

Factor of 814 are in pair so 841 is a perfect square

(iv) 1089 = 3×3×11×11

As the factor of 1089 are in pair so it is a perfect square

Given:

Difference between the square of two numbers is 63.

Calculation:

Let the numbers be x and y, where x > y

According to question.

⇒ x² - y² = 63

⇒ (x + y)(x - y) = 63

Factore of 63 are (63, 1), (21, 3) and (9, 7)

There will be 3 pairs whose square difference is 63.

The numbers will be 

⇒ x + y = 63

⇒ x - y = 1

So, pair one will be x = 32 and y = 31

⇒ x + y = 9

⇒ x - y = 7

So, pair one will be x = 8 and y = 1.

∴ Three pairs of natural number whose difference of square is 63.