Array of Strings in C++ (5 Different Ways to Create) - GeeksforGeeks

kartik Ahuja

greeksforgeeks

Array of Strings in C++ (5 Different Ways to Create)

Difficulty Level : Easy
Last Updated : 28 Oct, 2020

In C and C++, a string is a 1-dimensional array of characters and an array of strings in C is a 2-dimensional array of characters. There are many ways to declare them, and a selection of useful ways are given here.

1. Using Pointers:

We actually create an array of string literals by creating an array of pointers.

This is supported by both C and C++.

// C++ program to demonstrate array of strings using

// 2D character array

#include <iostream>

int main()

{

// Initialize array of pointer

const char *colour[4] = { "Blue", "Red",

"Orange", "Yellow" };

// Printing Strings stored in 2D array

for (int i = 0; i < 4; i++)

std::cout << colour[i] << "\n";

return 0;

}

Output:

BlueRedOrangeYellow

Number of strings are fixed, but needn’t be. The 4 may be omitted, and the compiler will compute the correct size.
These strings are constants and their contents cannot be changed. Because string literals (literally, the quoted strings) exist in a read-only area of memory, we must specify “const” here to prevent unwanted accesses that may crash the program.

2. Using 2D array:

This method is useful when the length of all strings is known and a particular memory footprint is desired. Space for strings will be allocated in a single block

This is supported in both C and C++.

// C++ program to demonstrate array of strings using

// 2D character array

#include <iostream>

int main()

{

// Initialize 2D array

char colour[4][10] = { "Blue", "Red", "Orange",

"Yellow" };

// Printing Strings stored in 2D array

for (int i = 0; i < 4; i++)

std::cout << colour[i] << "\n";

return 0;

}

Output:

BlueRedOrangeYellow

Both the number of strings and size of strings are fixed. The 4, again, may be left out, and the appropriate size will be computed by the compiler. The second dimension, however, must be given (in this case, 10), so that the compiler can choose an appropriate memory layout.
Each string can be modified, but will take up the full space given by the second dimension. Each will be laid out next to each other in memory, and can’t change size.
Sometimes, control over the memory footprint is desirable, and this will allocate a region of memory with a fixed, regular layout.

3. Using the string class:

The STL string class may be used to create an array of mutable strings. In this method, the size of the string is not fixed, and the strings can be changed.

This is supported only in C++, as C does not have classes.

// C++ program to demonstrate array of strings using

// array of strings.

#include <iostream>

#include <string>

int main()

{

// Initialize String Array

std::string colour[4] = { "Blue", "Red",

"Orange", "Yellow" };

// Print Strings

for (int i = 0; i < 4; i++)

std::cout << colour[i] << "\n";

}

Output:

BlueRedOrangeYellow

The array is of fixed size, but needn’t be. Again, the 4 here may be omitted, and the compiler will determine the appropriate size of the array. The strings are also mutable, allowing them to be changed.

4. Using the vector class:

The STL container Vector can be used to dynamically allocate an array that can vary in size.

This is only usable in C++, as C does not have classes. Note that the initializer-list syntax here requires a compiler that supports the 2011 C++ standard, and though it is quite likely your compiler does, it is something to be aware of.

// C++ program to demonstrate vector of strings using

#include <iostream>

#include <vector>

#include <string>

int main()

{

// Declaring Vector of String type

// Values can be added here using initializer-list syntax

std::vector<std::string> colour {"Blue", "Red", "Orange"};

// Strings can be added at any time with push_back

colour.push_back("Yellow");

// Print Strings stored in Vector

for (int i = 0; i < colour.size(); i++)

std::cout << colour[i] << "\n";

}

Output:

BlueRedOrangeYellow

Vectors are dynamic arrays, and allow you to add and remove items at any time.
Any type or class may be used in vectors, but a given vector can only hold one type.

5. Using the array class:

The STL container array can be use to allocate a fixed-size array. It may be used very similarly to vector, but the size is always fixed.

This is supported only in C++.

#include <iostream>

#include <array>

#include <string>

int main()

{

// Initialize array

std::array<std::string, 4> colour { "Blue", "Red", "Orange",

"Yellow" };

// Printing Strings stored in array

for (int i = 0; i < 4; i++)

std::cout << colour[i] << "\n";

return 0;

}

Output

BlueRedOrangeYellow

Notes:

These are by no means the only ways to make a collection of strings. C++ offers several container classes, each of which have various tradeoffs and features, and all of them exist to fill requirements that you will have in your projects. Explore and have fun!

Conclusion: Out of all the methods, Vector seems to be the best way for creating an array of Strings in C++.

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