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Strings are crucial components of any programming language, including C++. Understanding what strings are and how to use them efficiently is critical if you wish to store text, manipulate it, or accept keyboard inputs and outputs.
This tutorial will teach you everything you need to know about string handling and working in C++.
C++ defines a method for representing a sequence of characters as a class object. This class is known as std:: string. The string class holds characters as a sequence of bytes, with the ability to access single-byte characters.
Strings are most typically employed in programs that require us to operate with text. In C++, we may execute a variety of operations on strings. For example, reversing, concatenating, or passing a function argument.
C-style Strings (C-string)
The Standard C++ Library string class
The C-style String was invented in the C language and is still supported in C++. This string is a one-dimensional array of characters that ends with the null character '0'. Thus, a null-terminated string comprises the string's characters followed by a null.
The one that follows the declaration and initialization generate a string that contains the word "Logic" . The size of the character array holding the string must be one greater than the total number of characters in the word "Logic" to accommodate the null character at the very end of the array of characters.
As we create Integer Array, in that similar way we can create C-style string.
The array's length is one more than the string's length since we additionally need to include a null character in the array. As an alternative, we can define the string as follows:
Because C++ automatically inserts a null character at the end of the string, the array str_array will still hold 6 characters. If we use the sizeof() function to determine the size of the aforementioned array, it will return 6.
The memory presentation of the above-described string in C/C++ is shown below.
It is not required to use all of the available space in a character array (string):
Consider the following example, which shows how to utilize the character array to build and store a C-style string in a variable.
The C Standard Library includes a few useful functions for manipulating strings. While they are not usually suggested,
they can still be used in C++ programming by including the <
|strcpy(s1,s2)||Copies string s2 into string s1.|
|strcat(s1,s2)||Concatenates string s2 onto the end of string s1.|
|strlen(s1)||Returns the length of string s1.|
|strcmp(s1,s2)||Returns 0 if s1 and s2 are the same; less than 0 if s1|
|strchr(s1,ch)||Returns a pointer to the first occurrence of character ch in string s1.|
|strstr(s1,s2)||Returns a pointer to the first occurrence of string s2 in string s1|
|A string is a type of object that can be depicted as a sequence of characters.||A character array is merely a collection of characters that can be finished with a null character.|
|Memory is allocated dynamically in the case of strings. On the fly, more memory can be allocated. No memory is wasted since no memory is preallocated.||The size of the character array must be allocated statically; more memory cannot be allocated at run time. Unused allocated memory is also a waste of resources.|
|When compared to character arrays, strings are slower to implement.||Character array implementation is faster than std::string implementation.|
|The String class defines a number of functions that enable various string operations.||Character arrays don't have many built-in functions for manipulating strings.|
|Because strings are objects, there is no array decay.||In the case of the character array, there is a risk of array degradation.|
C-style strings are relatively harmful; if the string/char array is not null-terminated, it might result in a slew of issues. The std::string class provided by the C++ Standard Library is a considerably safer option. This is how you utilize it:
String concatenation is the process of joining two or more strings to create a new string. If we want to concatenate two or more strings, C++ provides the necessary capability.
This is a C++ program that checks two strings for equality.
A structure can be passed as a method argument in the same way that any other variable or pointer can.
C++'s string class includes a plethora of built-in functions. These functions are useful since they allow us to perform our activities more quickly. These string functions are as follows:
|Function||Description of Function|
|int compare(const string& str)||used to compare two string objects.|
|int length()||used to find the length of the string.|
|void swap(string& str)||used to swap the values of two string objects.|
|string substr(int pos,int n)||creates a new string object of n characters.|
|int size()||returns the length of the string in terms of bytes.|
|void resize(int n)||used to resize the length of the string up to n characters.|
|string& replace(int pos,int len,string& str)||replaces portion of the string that begins at character position pos and spans len characters.|
|string& append(const string& str)||adds new characters at the end of another string object.|
|char& at(int pos)||used to access an individual character at specified position pos.|
|int find(string& str,int pos,int n)||used to find the string specified in the parameter.|
|int find_first_of(string& str,int pos,int n||used to find the first occurrence of the specified sequence.|
|int find_first_not_of(string& str,int pos,int n )||used to search the string for the first character that does not match with any of the characters specified in the string.|
|int find_last_of(string& str,int pos,int n)||used to search the string for the last character of specified sequence.|
|int find_last_not_of(string& str,int pos)||searches for the last character that does not match with the specified sequence.|
|string& insert()||inserts a new character before the character indicated by the position pos.|
|int max_size()||finds the maximum length of the string.|
|void push_back(char ch)||adds a new character ch at the end of the string.|
|void pop_back()||removes a last character of the string.|
|string& assign()||assigns new value to the string.|
|int copy(string& str)||copies the contents of string into another.|
|char& back()||returns the reference of last character.|
|Iterator begin()||returns the reference of first character.|
|int capacity()||returns the allocated space for the string.|
|const_iterator cbegin()||points to the first element of the string.|
|const_iterator cend()||points to the last element of the string.|
|void clear()||removes all the elements from the string.|
|const_reverse_iterator crbegin()||points to the last character of the string.|
|const_char* data()||copies the characters of string into an array.|
|bool empty()||checks whether the string is empty or not.|
|string& erase()||removes the characters as specified.|
|char& front()||returns a reference of the first character.|
|string& operator+=()||appends a new character at the end of the string.|
|string& operator=()||assigns a new value to the string.|
|char operator(pos)||retrieves a character at specified position pos.|
|int rfind()||searches for the last occurrence of the string.|
|iterator end()||references the last character of the string.|
|reverse_iterator rend()||It points to the first character of the string.|
|void shrink_to_fit()||reduces the capacity and makes it equal to the size of the string.|
|char* c_str()||returns pointer to an array that contains null terminated sequence of characters.|
|const_reverse_iterator crend()||references the first character of the string.|
|reverse_iterator rbegin()||reference the last character of the string.|
|void reserve(inr len)||requests a change in capacity.|
|allocator_type get_allocator();||returns the allocated object associated with the string.|
You should now be convinced of the numerous advantages of std::strings over C-style strings. However, there are occasions when C-style strings are preferable:
If you come from a C background, you may be used to working with C-style strings.
Despite its advantages, a std::string is extremely complex. If you don't know what you're doing, it may get very complicated very quickly, much like the rest of the language. Furthermore, it consumes a large amount of memory, which may not be optimal for the purposes of your programs.
Given how short and lightweight C-style strings are, there is a performance gain to utilizing them if you are careful to manage your program's memory during runtime (by clearing an object's memory when you're done using it).
TThis article taught you everything there is to know about the C++ String class, character arrays, and the differences between the two. You've also gone over some of the most important in-built String class functions, as well as examples, that allow you to do various actions on strings. In C++, you can now use several functions to work with texts and strings. Learning to work with C++ strings is vital because your software may require you to take numerous inputs and produce results.
Good luck and happy learning!
In C++, a string is a sequence of characters. It represents a text or a sequence of characters enclosed in double quotes (" "). The string class in C++ provides a convenient way to work with strings, allowing you to perform various operations such as concatenation, searching, substring extraction, and more. Here's a detailed explanation of strings in C++:
1. String Class:
- C++ provides a string class called `std::string` in the `
- The string class is part of the Standard Template Library (STL) and offers a rich set of member functions to manipulate and access strings.
2. Declaration and Initialization:
- To declare and initialize a string variable, you can use the following syntax:
3. Basic String Operations:
- Length: You can obtain the length of a string using the `length()` or `size()` member function.
- Accessing Characters: You can access individual characters in a string using the indexing operator ().
- Concatenation: Strings can be concatenated using the `+` operator or the `append()` member function.
- Substring Extraction: You can extract substrings from a string using the `substr()` member function.
- String Comparison: You can compare strings using the `==`, `!=`, `<`, `>`, `<=`, and `>=` operators.
- Searching: You can search for substrings within a string using functions like `find()` or `rfind()`.
4. Manipulating Strings:
- The string class provides various member functions to manipulate strings, such as converting cases (`tolower()`, `toupper()`), trimming whitespace (`erase()`, `find_first_not_of()`), replacing characters (`replace()`), and more.
5. Additional Functionality:
- C++ provides several additional functionalities for working with strings, including string input/output, string streams (`std::stringstream`), regular expressions (`std::regex`), and more.
Using the string class in C++, you can efficiently work with textual data and perform a wide range of operations on strings. It provides a convenient
In C++, there are two types of strings: C-style strings and C++ strings (std::string). Let's explore each type in detail:
1. C-Style Strings:
- C-style strings are character arrays terminated by a null character ('\0') and are defined using the `char` data type.
- The elements of a C-style string are individual characters stored in consecutive memory locations.
- To create and initialize a C-style string, you declare a character array and assign a sequence of characters to it, including the null character at the end.
- For example:
- C-style strings have certain characteristics and limitations:
- They are mutable, meaning you can modify the individual characters in the string.
- They are null-terminated, which allows functions to determine the end of the string by searching for the null character.
- You need to be cautious when working with C-style strings to avoid buffer overflow and memory access errors.
2. C++ Strings (std::string):
- C++ strings are part of the Standard Template Library (STL) and are defined by the `std::string` class in the `< string >` header.
- C++ strings are objects that provide a higher-level and safer way to work with strings compared to C-style strings.
- The std::string class offers a wide range of member functions to manipulate and access strings.
- To create and initialize a C++ string, you can use the `std::string` class constructor or assignment operator:
- C++ strings have several advantages over C-style strings:
- They are dynamically resizable, allowing you to easily add, remove, or modify characters in the string.
- They automatically manage memory allocation and deallocation, preventing common memory-related issues.
- They provide a rich set of member functions, such as concatenation, substring extraction, searching, and more.
- They support operator overloading, allowing you to use operators like `+`, `==`, `<`, etc., with strings.
- C++ strings provide a safer and more convenient alternative to C-style strings, making them the preferred choice for string manipulation in modern C++ programming.
In summary, C-style strings are character arrays terminated by a null character and defined using the `char` data type. C++ strings (std::string), on the other hand, are objects of the `std::string` class and offer higher-level functionalities and safety compared to C-style strings. C++ strings are dynamically resizable, automatically manage memory, and provide a rich set of member functions for string manipulation.
In C++, you can declare a string using the `std::string` class from the Standard Template Library (STL). Here's how you can declare a string in detail:
1. Include the Necessary Header File:
- Before declaring a string, make sure to include the `< string >` header file in your code:
2. Declare a String Variable:
- To declare a string variable, use the `std::string` class followed by the variable name. You can choose any valid variable name according to your preference:
3. Initialize the String:
- You can initialize the string at the time of declaration or assign a value to it later:
- Initialization at declaration:
- Initialization after declaration:
4. Assign a Value to the String:
- After declaration, you can assign a value to the string using the assignment operator (`=`):
5. Access and Modify the String:
- Once the string is declared and assigned a value, you can access and modify its contents:
- Accessing the string's value:
- Modifying the string's value:
6. Concatenation and Manipulation:
- You can concatenate strings using the `+` operator or the `+=` operator:
- The `std::string` class provides a wide range of member functions to manipulate strings, such as finding substrings, extracting substrings, replacing characters, converting cases, and more.
By following these steps, you can declare a string variable in C++. Once declared, you can initialize it with a value at the time of declaration or assign a value to it later. You can access, modify, concatenate, and manipulate the string using the various member functions provided by the `std::string` class.
In C++, the `size()` member function is used to determine the size or length of a string. It belongs to the `std::string` class from the Standard Template Library (STL). Here's a detailed explanation of the `size()` function:
1. Function Syntax:
- The `size()` function is invoked on a `std::string` object and returns the size or length of the string.
- The function has the following syntax:
2. Return Value:
- The `size()` function returns the number of characters in the string as an integer value.
- The returned value represents the length of the string, excluding the null terminator character.
- For example, if the string is "Hello", the `size()` function will return 5.
3. Usage Examples:
- Basic Usage:
- Looping over Characters:
- Conditional Checks:
4. Note on Unicode Characters:
- The `size()` function returns the number of characters in the string, not the number of bytes.
- If your string contains Unicode characters, each character may occupy multiple bytes, and the `size()` function will still return the correct character count.
5. Alternative Functions:
- The `size()` function is equivalent to the `length()` function. Both functions return the same value and can be used interchangeably.
In summary, the `size()` function in C++ returns the size or length of a string by counting the number of characters in the string. It is a member function of the `std::string` class and is commonly used to determine the length of a string for various purposes, such as loops, conditional checks, and string processing operations.
In C++, there are multiple ways to access the characters in a string. Here are the different methods you can use to access individual characters in a C++ string:
1. Indexing Operator (``):
- The indexing operator allows you to access individual characters in a string by their position, starting from index 0.
2. At() Function:
- The `at()` member function of the `std::string` class allows you to access characters in a string, similar to the indexing operator.
3. Iteration with Range-based for Loop:
- You can use a range-based for loop to iterate over each character in a string.
- The `std::string` class provides iterators to traverse through the characters of a string.
5. C-Style Character Array:
- You can access individual characters in a string by treating it as a C-style character array.
These methods allow you to access characters in a C++ string based on your specific requirements. The indexing operator and `at()` function provide direct access to individual characters by their positions. Iterating over the string using a range-based for loop or iterators allows you to access each character sequentially. Additionally, you can obtain a C-style character array from the string and access characters using standard C-style array operations. Choose the method that suits your needs and the context of your application.
In C programming, a string is a sequence of characters stored in consecutive memory locations. In C, strings are represented as arrays of characters terminated by a null character ('\0'). Here's a detailed explanation of strings in C:
1. String Declaration:
- In C, strings are declared as character arrays, where each element of the array holds a character of the string.
- The declaration follows the syntax:
- The size of the character array is determined automatically based on the number of characters in the string plus one additional space for the null character.
2. String Initialization:
- Strings in C can be initialized at the time of declaration or assigned a value later.
- Initialization at declaration:
- Initialization after declaration:
3. Accessing and Modifying Strings:
- Individual characters in a C string can be accessed and modified using array indexing:
4. String Manipulation:
- C provides several standard library functions to manipulate strings, including:
- `strlen()`: Returns the length of a string.
- `strcpy()`: Copies one string to another.
- `strcat()`: Concatenates two strings.
- `strcmp()`: Compares two strings for equality.
- `strchr()`: Searches for a specific character in a string.
- `strstr()`: Searches for a substring within a string.
- These functions operate on C-style strings and require including the `< string.h >` header.
5. Input and Output:
- Strings can be input from the user using the `scanf()` function or read from a file using functions like `fscanf()` or `fgets()`.
- Strings can be output to the console using the `printf()` function or written to a file using functions like `fprintf()` or `fputs()`.
6. String Limitations:
- C-style strings have a few limitations, such as:
- They are mutable, meaning you can modify individual characters.
- You need to ensure that the string remains within the allocated memory to avoid buffer overflow issues.
- They do not have built-in functions for common string operations like concatenation or substring extraction.
In summary, strings in C are represented as character arrays terminated by a null character. They are manipulated using standard library functions and can be accessed and modified using array indexing. However, C-style strings have some limitations and lack built-in functions for string manipulation. Therefore, additional care and manual manipulation are required when working with strings in C.
In C++, there are several ways to compare two strings. Here are the different methods you can use to compare C++ strings in detail:
1. Equality Operator (`==`):
- The equality operator (`==`) compares two strings and returns `true` if they are equal, and `false` otherwise.
- It compares the content of the strings character by character.
2. Inequality Operator (`!=`):
- The inequality operator (`!=`) compares two strings and returns `true` if they are not equal, and `false` otherwise.
- It also compares the content of the strings character by character.
3. Relational Operators (`<`, `<=`, `>`, `>=`):
- The relational operators compare two strings lexicographically (based on dictionary order) character by character.
- They return `true` if the comparison condition is satisfied, and `false` otherwise.
4. String Comparison Functions:
- The `< cstring >` header provides additional functions for comparing C++ strings, such as `strcmp()`, `strncmp()`, `strcasecmp()`, etc.
- These functions compare strings character by character and return an integer value indicating the result of the comparison.
5. Lexicographical Comparison Functions:
- The `< algorithm >` header provides lexicographical comparison functions like `std::lexicographical_compare()` and `std::lexicographical_compare_three_way()`.
- These functions compare two ranges of characters or strings lexicographically and return a boolean value indicating the result of the comparison.
The main difference between a C++ string and a C string lies in how they are represented and manipulated. Here's a detailed explanation of the differences between C++ strings and C strings:
- C++ String: C++ strings are represented by the `std::string` class from the Standard Template Library (STL). They are objects that encapsulate a sequence of characters. The size of a C++ string is dynamic, and memory management is handled automatically.
- C String: C strings are represented as character arrays terminated by a null character (`'\0'`). They are sequences of characters stored in consecutive memory locations. The size of a C string is fixed and determined by the number of characters in the array.
2. Null Termination:
- C++ String: C++ strings do not require explicit null termination. The `std::string` class internally manages the size and null termination of the string, allowing you to focus on string manipulation without worrying about null characters.
- C String: C strings must be explicitly null-terminated. The null character (`'\0'`) is placed at the end of the character array to indicate the termination of the string. This is required because C string functions rely on null termination to determine the end of the string.
3. Memory Management:
- C++ String: C++ strings handle memory management automatically. They can dynamically grow or shrink to accommodate the required size. The memory allocation and deallocation are managed internally by the `std::string` class.
- C String: C strings require manual memory management. You need to allocate memory for the character array using functions like `malloc()` or `calloc()`, and deallocate the memory using `free()` when it is no longer needed. This manual memory management can be error-prone and lead to issues such as buffer overflow or memory leaks if not handled carefully.
4. Size and Length:
- C++ String: C++ strings provide member functions like `size()` or `length()` to retrieve the number of characters in the string. The size of a C++ string is not limited by the maximum size of an array, and it can vary dynamically.
- C String: C strings do not have built-in functions to directly retrieve the length. You need to use the `strlen()` function from the `
5. String Manipulation:
- C++ String: C++ strings provide a wide range of member functions to manipulate strings, such as concatenation, substring extraction, searching, replacing, and more. These member functions simplify string manipulation and offer a higher-level abstraction.
- C String: C strings rely on a set of string manipulation functions from the `< string.h >` header, such as `strcpy()`, `strcat()`, `strcmp()`, etc. These functions operate on character arrays and require manual handling of null termination, memory allocation, and buffer sizes.
6. Error Handling:
- C++ String: C++ strings provide a safer programming environment by handling memory management and error conditions internally. They perform automatic bounds checking and memory allocation, reducing the risk of buffer overflows and memory-related issues.
- C String: C strings require manual error handling and memory management. Developers need to be cautious to avoid buffer overflow, buffer size miscalculations, or memory leaks.
In summary, C++ strings (std::string) provide a higher-level and safer way to work with strings compared to C strings. C++ strings handle memory management internally, dynamically resize as needed, and provide a rich set of member functions for string manipulation. C strings (character arrays) require manual memory management, explicit null termination, and rely on C library functions for string manipulation. C strings are more low-level and require careful handling to avoid errors.
The syntax of a string depends on the programming language you are using. Here, I'll explain the syntax of strings in two commonly used programming languages: C++ and Python.
- C++ strings are represented by the `std::string` class from the Standard Template Library (STL). The syntax for declaring and initializing a C++ string is as follows:
- In C++, strings are enclosed in double quotes (`"..."`). The double quotes indicate that the text within them is a string literal.
- C++ strings can also be concatenated using the `+` operator:
- In Python, strings can be declared and initialized using single quotes (`'...'`) or double quotes (`"..."`):
- Python allows multiline strings, which can be created using triple quotes (`'''...'''` or `"""..."""`):
- Python strings support string interpolation using f-strings (formatted strings):
Both C++ and Python provide various operations and methods to manipulate strings, such as accessing individual characters, concatenation, substring extraction, search, and replace. The specific syntax and available operations may vary between programming languages, but strings are a fundamental data type in most programming languages and offer flexibility in representing and manipulating textual data.
Using C++ strings (std::string) offers several advantages over traditional C-style strings (character arrays). Here are the key advantages of using C++ strings:
1. Dynamic Memory Management:
- C++ strings handle memory management automatically. They dynamically allocate and deallocate memory for storing the string content.
- With C++ strings, you don't need to worry about manually allocating memory, calculating buffer sizes, or dealing with potential buffer overflow issues.
- The memory allocation and deallocation are handled internally by the std::string class, providing a safer and more convenient approach to managing strings.
2. Flexibility in Size:
- C++ strings can grow or shrink dynamically based on the needs of your program.
- Unlike C-style strings, which have a fixed size determined at compile-time, C++ strings can change their size during runtime, accommodating strings of varying lengths without any limitations.
- This flexibility allows you to work with strings of different sizes without the need for preallocating fixed-size buffers.
3. Convenience and Ease of Use:
- C++ strings provide a high-level abstraction and a rich set of member functions specifically designed for string manipulation.
- These member functions offer a wide range of operations such as concatenation, substring extraction, searching, replacing, and more.
- The availability of these functions simplifies the implementation of string-related tasks and reduces the need for manual string manipulation algorithms.
4. Safer String Handling:
- C++ strings provide built-in bounds checking, preventing common programming errors such as buffer overflows.
- The std::string class ensures that string operations stay within the allocated memory, reducing the risk of memory corruption and undefined behavior.
- Additionally, C++ strings are null-terminated internally, which eliminates the need for explicit null termination and avoids related issues.
5. Compatibility with Standard Library:
- C++ strings are part of the Standard Template Library (STL) and integrate well with other components of the C++ standard library.
- They can be easily used with other STL containers, algorithms, and data structures, providing a consistent and unified approach to working with data in C++.
- This compatibility enables you to leverage the vast collection of STL utilities and simplifies code development and maintenance.
In summary, using C++ strings provides numerous advantages, including automatic memory management, dynamic sizing, convenience in string manipulation, improved safety, and compatibility with the C++ standard library. C++ strings offer a higher-level abstraction and alleviate many of the complexities associated with traditional C-style strings, allowing for more efficient and reliable string handling in your programs.