Write a program that inputs a telephone number as a string in the form (555) \(555-5555 .\) The program should use function strtok to extract the area code as a token, the first three digits of the phone number as a token, and the last four digits of the phone number as a token. The seven digits of the phone number should be concatenated into one string. Both the area code and the phone number should be printed.

In C++, string tokenization is a powerful tool for dissecting a string into multiple segments, called tokens, based on specified delimiters. The strtok function is a classic function used in this process. It comes from the C library and is also available in C++ through the cstring or string.h header. Understanding how to use strtok is fundamental for many text-parsing tasks.

The function works by taking two arguments: the string you want to tokenize and a string containing all possible delimiters. On the first call, strtok takes the string to be tokenized, and on subsequent calls, it should be passed NULL to indicate continuation from where it left off. The function then returns a pointer to the next token, or NULL when no more tokens are available.

In our exercise, we used strtok to extract different components of a telephone number. Delimiters like parentheses and hyphens were used to isolate the area code and phone number segments. Each call to strtok gives us the next segment of the phone number until the entire sequence is processed. Knowing how to implement and sequence calls to strtok is a critical skill in C++ programming for data parsing tasks.

String manipulation involves altering, dissecting, and recombining strings to achieve a desired output. In C++, strings can be manipulated in numerous ways, including tokenization, concatenation, searching, and more. The standard string class provides a rich set of functions that make these tasks easier, but traditional C-style string manipulation functions - like those found in cstring - are still widely used for simplicity and direct control over strings.

After tokenizing the input string using strtok, we perform another common operation: concatenation. This is the process of appending one string to the end of another to create a single string. This technique was used to join the two parts of the phone number in our exercise. While C++'s string class offers convenient concatenation using the + operator, C-style strings require careful handling with functions like strcat or by manually iterating and combining the characters. String manipulation is ubiquitous in programming, and mastering it in C++ requires practice and an understanding of both the string class and C-style string functions.

Grasping the basics of C++ programming is vital for solving a wide range of problems, from simple to complex. C++ is a versatile language that supports procedural, object-oriented, and generic programming paradigms. For beginners, it's essential to learn the syntax, data types, control structures, functions, and standard library utilities, like input/output operations and string handling.

In the exercise, we included headers such as stdio.h for Input/Output operations using functions like printf and scanf, and string.h for string manipulation functions such as strtok. These headers provide access to a wide variety of functions that are a part of the standard C and C++ libraries.

The problem-solving process typically begins with understanding the problem and then follows a structured approach involving reading input, processing data, and producing output. This step-by-step methodology, demonstrated in the exercise to extract and format a telephone number, serves as a great example of how fundamental C++ programming constructs can be applied to real-world problems.