Question

Write the definition of ptr, a constant pointer to an int.

Short answer

To define a constant pointer to an integer in C++, first, declare an integer variable and then write a constant pointer definition initializing it with the address of the integer variable. 1. Declare an integer variable, for example 'x': ```cpp int x = 10; ``` 2. Define the constant pointer 'ptr' initialized with the address of 'x': ```cpp int *const ptr = &x ``` The resulting code is: ```cpp int x = 10; int *const ptr = &x ``` Here, 'ptr' will point to the integer variable 'x' and will not be able to point to any other variable since it is a constant pointer.

Step-by-step solution

Declare an int variable

Declare an integer variable, for example 'x', to which the pointer will point to. This could be simply written as: ```cpp int x = 10; ```

Write the constant pointer definition

Now we can define 'ptr' as a constant pointer to an integer. It should be initialized when it's declared so that its value cannot change later. The definition should include the keyword 'const' and an asterisk (*) to denote that it's a pointer. Here's the correct definition: ```cpp int *const ptr = &x ``` This definition is saying that 'ptr' is a constant pointer to an integer, and its address value is set to the address of 'x', making it point to 'x'. Since it's a constant pointer, its address value cannot be changed after this line.