String Manipulations in C++
In the C++ programming language, the string data type is handled in two main ways. The C-style string character array in a C++ program is a string data type handling library, which we analyzed earlier. std::string is a built-in function or feature of the standard library in C++ programming. It provides a higher-level data information abstraction method for string data type methods in C++ programs.
In advanced C++ programming, the std::string class library is a desirable choice for string manipulation due to its ease, safety, and built-in functions. These features will primarily focus on handling and managing std::string in C++ programming.
Basic Operations with std::string in C++ Programming.
The std::string class library in C++ provides a variety of built-in functions and features for handling and managing strings. C++ users can perform multiple string character operations using these class library functions.
So, let’s take a closer look at some common std::string class library operations.
Declaring and initializing a std::string in C++.
C++ users can declare and initialize the desired string character data type element in the std::string class library using these methods.
Example of Declaring and initializing a std::string.
#include <iostream>
#include <string> // Here we use std::string for string data type operations in C++
int main() {
std::string text1 = “Vcanhelpsu, Edtech”; // Here we declare a string literal data type
std::string text2 = text1; // Here we copy another string into
std::string text3 = text1;
std::cout << text1 << std::endl; // Result is – Vcanhelpsu, Edtech
std::cout << text2 << std::endl; // Result is – Vcanhelpsu, Edtech
std::cout << text3 << std::endl; // Result is – Vcanhelpsu, Edtech
return 0;
}
std::string class library basic operations in C++ program.
String length (size() or length()) concept of the std::string class library.
C++ users can find the current length of a std::string by applying the size() or length() built-in string function in a program. In this, we can analyze both the user-defined and declared string data type element equality sizes.
Example of String length (size() or length()).
#include <iostream>
#include <string>
int main() {
std::string c_name = “Vcanhelpsu Edtech”;
std::cout << “Size of company name text – ” << c_name.size() << std::endl; // Result – 17
std::cout << “Length of company name string – ” << c_name.length() << std::endl; // Result – 17
return 0;
}
Accessing characters is a concept of the std::string class library.
C++ users can access and display individual characters in a user-declared string data type by indexing or applying the at() function. The at() function is more efficient and secure in a C++ program because it checks user-defined string bounds.
Example of accessing characters concept of the std::string class library.
#include <iostream>
#include <string>
int main() {
std::string c_name = “Vcanhelpsu”;
// Here we access the character of the string using the storage element indexing method
std::cout << “First character of string – ” << c_name[0] << std::endl; // Result is – V
// Here we access the character of the string using the at() function bounds checked method
std::cout << “Second character of string – ” << c_name.at(1) << std::endl; // Result is – c
return 0;
}
Modifying a string concept of the std::string class library.
C++ users can modify a string in a program by assigning a new value to it, adding a new element to an existing string, or updating or replacing characters in an existing string.
Assigning a new string.
std::string c_name = “Vcanhelpsu”;
c_name = “Edtech”; // Now the c_name string variable holds the text value “Edtech”.
Adding string elements using the += or append() function.
std::string c_name = “Vcanhelpsu”;
c_name += “Edtech”; //Add using the `+=` operator.
std::cout << c_name << std::endl; // Result – Vcanhelpsu Edtech
c_name.append(“#”);
std::cout << c_name << std::endl; // Result – Vcanhelpsu Edtech#
Replacing string characters at a specific position.
std::string c_name = “Vcanhelpsu”;
c_name[0] = ‘V’; // Displays the first character here as ‘V’.
std::cout << c_name << std::endl; // Result – Vcanhelpsu
Replacing a substring in the std::string class library using the replace() function.
#include <iostream>
#include <string>
int main() {
std::string text = “Vcanhelpsu, Platform”;
// here we Replace substring index 10 to 11 with a new user defined string
text.replace(10, 11, “Edtech”);
std::cout << text << std::endl; // Result – Vcanhelpsu Edtech
return 0;
}
String concatenation is a concept of the std::string class library.
C++ users can concatenate two different strings of text data by applying the + operator or the append() built-in function method in a program.
Example of String concatenation is a concept of the std::string class library.
#include <iostream>
#include <string>
int main() {
std::string text1 = “Vcanhelpsu”;
std::string text2 = “Edtech”;
// Here it concatenates text with the ‘+’ operator to add two different strings.
std::string output = text1 + ” ” + text2;
std::cout << output << std::endl; // Result – Vcanhelpsu Edtech
// Here it concatenates text with the ‘append()’ operator to add two different strings.
text1.append(” “).append(text2);
std::cout << text1 << std::endl; // Result – Vcanhelpsu Edtech
return 0;
}
String comparison concept of the std::string class library.
C++ users can compare two different strings in a program by applying comparison operators or the compare() built-in function method.
Example of String comparison concept of the std::string class library.
#include <iostream>
#include <string>
int main() {
std::string text1 = “Bhavishi”;
std::string text2 = “Siddhi”;
if (text1 == text2) {
std::cout << “Both text strings are equal.” << std::endl;
} else {
std::cout << “Both text strings are different.” << std::endl; // Result – Both text strings are different.
}
return 0;
}
The compare() function is a concept of the std::string class library.
- The compare() function provides some built-in features for C++ user programs.
- If both user-defined text strings are equal, the output is 0.
- If the user-defined first string is lexicographically smaller than the second string, it is itself a negative value.
- If the user-defined first string is lexicographically larger than the second, it is a positive value.
Example of the compare() function concept.
#include <iostream>
#include <string>
int main() {
std::string text1 = “Java”;
std::string text2 = “Python”;
if (text1.compare(text2) == 0) {
std::cout << “Here both text strings are equal in nature.” << std::endl;
} else if (text1.compare(text2) < 0) {
std::cout << “Here text1 is lexicographically lower than text2.” << std::endl;
} else {
std::cout << “Here text1 is lexicographically higher than text2.” << std::endl;
}
return 0;
}
Substring concept of the std::string class library.
C++ users can extract a smaller substring from a larger text string by applying the substr() function to a program.
You must have two required parameters for this.
- The starting string position (index).
- The length of the current substring (optional).
Example of Substring is a concept.
#include <iostream>
#include <string>
int main() {
std::string c_name = “Vcanhelpsu, Edtech”;
// Extract the substring text starting from position 11 with length 8
std::string subtext = c_name.substr(11, 8);
std::cout << “Here is the substring text of c_name – ” << subtext << std::endl; // Result – Here is the substring text of c_name – Edtech
return 0;
}
String search is a concept of the std::string class library.
C++ users can search for a substring or character in an existing string by applying the find() or rfind() function methods to a program.
Example of finding a character or substring.
#include <iostream>
#include <string>
int main() {
std::string c_name = “Vcanhelpsu,Edtech”;
// here we Find the first text string occurrence of ‘p’
size_t loc = c_name.find(‘p’);
if (loc != std::string::npos) {
std::cout << “‘p’ character found at location – ” << loc << std::endl; // Result – 7
} else {
std::cout << “‘p’ character not found -” << std::endl;
}
// here it Find a substring in complete above string
loc = c_name.find(“Edtech”);
if (loc != std::string::npos) {
std::cout << “‘Edtech’ word found at location – ” << loc << std::endl; // Result – 12
}
return 0;
}
Explanation of finding a character or substring.
- In this program, the find() function indicates the current position location of the first occurrence of the current substring or character.
- In this example, npos is a constant that displays the information “‘Edtech’ word found at location” in the current program.
Finding the last occurrence (rfind()) function.
#include <iostream>
#include <string>
int main() {
std::string text = “Java, Python Matlab”;
// Find the last occurrence of the “Matlab” text string
size_t loc = text.rfind(“Matlab”);
if (loc != std::string::npos) {
std::cout << “Here ‘Matlab’ text found at location – ” << loc << std::endl; // Result – 13
}
return 0;
}
String input/output concept of the std::string class library.
C++ users can use the std::cin and std::cout statement methods to read and print an existing text string in a program.
Example of reading a String input/output.
#include <iostream>
#include <string>
int main() {
std::string message;
std::cout << “Enter a desired text message – “;
std::getline(std::cin, message); // here it reads the entire text line, including white spaces
std::cout << “Your input text message is – ” << message << std::endl;
return 0;
}
Explanation of reading a String input/output.
- Here in this program, the std::getline() library function reads the entire text line, including white spaces.
- Here, std::cin >> message; It reads input up to the first empty space entered by the user. It cannot be used for text strings with too many spaces.
