Question

include #include using namespace std; int main() { string str1 = "Trip to Hawaii"; string str2 = "Summe… # What is the output of the following program? #include #include using namespace std; int main() { string str1 = "Trip to Hawaii"; string str2 = "Summer or Fall"; string newStr; newStr = str2 + ' ' + str1; 500 | Chapter 7: User-Defined Simple Data Types, Namespaces, and the string Type C7952_CH07 cout << newStr << endl; cout << str1 + " in " + str2 << endl; cout << newStr.length() << endl; cout << str1.find('H') << endl; cout << str2.find("or") << endl; cout << newStr.substr(10, 19) << endl; cout << newStr.replace(23, 6, "******") << endl; string str = "C++ Programming"; cout << str << endl; cout << str.length() << endl; str[0] = 'J'; str[2] = '$'; cout << str << endl; return 0; }

Short answer

The output will show concatenated and manipulated strings, string lengths, and specific indices of characters or substrings.

Step-by-step solution

Understanding String Concatenation

The program begins by declaring three string variables: `str1` with the value "Trip to Hawaii", `str2` with the value "Summer or Fall", and `newStr`, which will hold the result of concatenating `str2`, a space, and `str1`. Thus, `newStr` will be "Summer or Fall Trip to Hawaii".

Outputting Concatenated Strings

The first output command `cout << newStr << endl;` prints the concatenated string `newStr`, which is "Summer or Fall Trip to Hawaii". The second output command prints `str1` followed by " in " and `str2`, resulting in "Trip to Hawaii in Summer or Fall" being displayed.

Calculating String Length

The third output uses `newStr.length()`, which calculates and prints the length of `newStr`. "Summer or Fall Trip to Hawaii" contains 30 characters, so `30` is printed.

Finding Character Index

The fourth output uses `str1.find('H')` to find the index of 'H' in `str1`. In "Trip to Hawaii", 'H' is at index 8, therefore the program prints `8`.

Finding Substring Index

The fifth output uses `str2.find("or")` to locate the substring "or" in `str2`, which is found starting at index 7. So, `7` is printed.

Extracting a Substring

The sixth output uses `newStr.substr(10, 19)` to extract a substring from `newStr`, starting from index 10 and extracting 19 characters. This extracts "r Fall Trip to Ha".

Replacing a Substring

The seventh output uses `newStr.replace(23, 6, "******")`, which replaces 6 characters starting from index 23 in `newStr` with "******". The modified string becomes "Summer or Fall Trip to Ha******".

Displaying a String and Modifying It

The program declares `str` as "C++ Programming" and outputs it. Subsequently, the length `17` is printed as it has 17 characters.

Modifying Characters in String

The task modifies `str` where `str[0]` becomes 'J' and `str[2]` becomes '$'. The altered string "J$+ Programming" is then printed.

Key concepts

String Concatenation

In C++, string concatenation combines two or more strings into a single string. This is often achieved using the `+` operator. When concatenating strings, additional elements like spaces can also be included to form a coherent text. For example, given two strings `str1` and `str2`, if we want to combine these and add a space between them, we would write `newStr = str2 + ' ' + str1;`. This operation results in a new string, `newStr`, containing both original strings separated by a space.
Concatenation is incredibly useful when needing to build large strings from smaller components, allowing for dynamic message creation or data formatting.

String Methods

C++ provides a variety of built-in string methods that enable various operations on string objects. These methods simplify common tasks such as searching and modifying strings.

• **Finding Characters or Substrings**: The `.find()` method is used to locate a particular character or substring within a string. It returns the index of the first occurrence, or `std::string::npos` if the substring is not found. For instance, `str1.find('H')` locates where 'H' first appears in `str1`.
• **Length of a String**: The `.length()` or `.size()` methods return the number of characters in the string. This is useful for understanding how much data a string currently contains, such as checking if input falls within size limits.
• **Extracting Substrings**: The `.substr()` method creates a new string from a portion of an existing string, specified by a starting index and length. This can be handy when only part of the string is needed for further processing.
• **Replacing Substrings**: The `.replace()` method allows for substitutions within a string, changing all characters from a starting index for a specified length with a new sequence of characters.

Each of these methods enhances the utility of string objects, allowing for flexible and powerful string manipulation.

String Modification Techniques

Modification of strings in C++ can be accomplished through direct character access or using more advanced methods like replacing blocks of text. With strings being sequences of characters, each character can be accessed and modified individually using bracket notation. For instance, `str[0] = 'J';` changes the first character of `str` to 'J'. This kind of modification enables fine control over specific parts of a string, ideal for corrections or dynamic content updates.
Additionally, methods like `.replace()` allow for not just individual character changes but also modifications of entire substrings. One can replace sections of a string with characters or entirely new strings. This approach is particularly beneficial when dealing with structured data transformations, such as censoring parts of a document or formatting code or text dynamically.
By combining direct character manipulation with method-driven modifications, C++ gives you tools to adeptly manage and adapt strings to suit varied programming needs.