C++ Fundamentals: Understanding the Basics

Learn about Strings in C++

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Introduction

An orderly series of characters is referred to as a string. In C++, a class object can be used to represent a string of characters. A String class is the type of class that offers such a definition. The single-byte character may be accessed thanks to the capabilities provided by the String class, which saves characters as a series of bytes. Double quotes are used as enclosing delimiters in C++.

String Class and Character Array Difference

String class	Character Array
The class "String" contains objects that may be expressed as a stream of characters.	A character array is just a collection of characters.
Strings are an example of a data type where memory is allocated dynamically, allowing for runtime demand-driven memory allocation.	Additional space cannot be provided at runtime if it is needed since the character array's size must be allocated statically.
Numerous features defined by the string class enable a variety of actions on strings.	There aren't many built-in functions for manipulating strings in character arrays.
When compared to implementation, strings take longer than the character array.	A character array can be implemented more quickly.

Declare and Initialize Strings in C++

In C++, initializing a string is rather easy.

using namespace std;

string std_string; Or std::string std_string;

#include <iostream>

using namespace std;
int main () {
char ch[12] = {'B', 'O', 'A', 'R', 'D', ' ', 'b', 'y',' ', 'c', 'h', ''};

string st = "Hello by st";
std::string std_st = "Hello by std_st";

cout << ch << endl;
cout << st << endl;
cout << std_st << endl;

return 0;
}

Output:

BOARD by ch

Hello by st

Hello by std_st

write your code here: Coding Playground

Both the initialization methods for the string class (st and std st) and the character array (ch) have been demonstrated in this example. As a starting point, we applied the character array technique by creating the character array ch[12], which has 12 entries and ends with a nil character. We applied a string class method in the second section.

Operations on Strings in C++

There are numerous built-in methods in C++ to modify strings, which is a benefit of utilizing the string class. Programming is now simple and efficient. Let's examine a few crucial string manipulation methods and learn about them through various examples.

String Size: The size of the object may be determined using the length() and size() methods.

cout << st.length() <<endl;
cout << st.size() <<endl;

Output:

String Concatenation: Concatenating strings is as simple as applying the + operator between two or more strings.

string new_string = st + " and " + std_st;
cout << new_string <<endl;

Output:

Hello by st and Hello by std_st

Appending Strings: A string can be concatenated and added to at a precise character place by using the class member function.append(string). If a programmer uses the syntax str.append(str1, p, n), then the string str will have n characters from position p added to the end.

string str = "I enjoy learning ";
string str1 = "Python, C++, or C";

str.append(str1, 8, 3);
cout << str << endl;

Output:

I enjoy learning C++

Searching strings: The find() member function can be used to locate the first instance of a string inside another. find() will start searching for a string needle inside a string haystack at position pos and return the location of the needle's first appearance. Similar to find(), rfind() only returns the final instance of the provided string.

string haystack = "Hello World!";
string needle = "o";
cout << haystack.find(needle)<<endl;
cout << haystack.find(needle, 4)<<endl;
cout << haystack.find(needle, 5)<<endl;
cout << haystack.find(needle, 8)<<endl;

Output:

4294967295

The index of the first instance of the letter "o" in the haystack string is "4", which will be printed by the first cout command. If we need the "o" in "World," we must change "pos" such that it points beyond the very first instance. The results of haystack.find(needle, 4) and haystack.find(needle, 5) were both 4 and 7, respectively. Find() returns std::string::npos if the substring cannot be located. Npos is a unique value that is equal to the largest value the type size type may represent. It is 4294967295 here. It is often used by functions that anticipate a string index as the end of the string indicator or by functions which return a string index as the error indicator.

This little code snippet finds every instance of "C++" in str2 and reports their locations:

string str2= "C++ is an object-oriented programming language and includes classes, inheritance, polymorphism, data abstraction and encapsulation.C++ allows exception handling, and function overloading which are not possible in C.C++ is a powerful, efficient and fast language.";

for(string::size_type i = 0, tfind; (tfind = wikistr.find("C++", i)) != string::npos; i = tfind + 1)
{
std::cout << "Found occurrence of 'C++' at position " << tfind << std::endl;
}

Output:

Found occurrence of 'C++' at position 0

Found occurrence of 'C++' at position 132

Found occurrence of 'C++' at position 217

Conclusion

This marks the conclusion of our discussion of strings in C++.

Learn about Strings in C++

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C++ Language: An Overview

Difference Between C and C++ Programming Languages

Understanding Loops in C++

Command Line Arguments in C++

Learn about Strings in C++

Initializing Vectors in C++

Understanding Vectors in C++

Understanding 2D Vectors in C++

Vector erase() in C++

Understanding Templates in C++

A quick guide to Unordered Map in C++

Left Shift Operator in C++

Bitwise Operators In C++

rand() Function in C++

Static variables in C++

Introduction

String Class and Character Array Difference

Declare and Initialize Strings in C++

Operations on Strings in C++

Conclusion