Strings

String is a sequence of symbols. All of the symbols can be accessed via their indexes starting from 0.

Indexes

Let's say we have the string "computer". It's structure is the following:

So if we need to print the first letter (c) and the 3rd letter (m), we do:

string word = "computer"; cout << word[0] << " " << word[2];

Output:

c m

Each string is terminated with a special character '\0'. If printed an empty space is shown.

Example

string word = "computer"; cout << word[1] << "*" << word[8] << "*" << word[7];

Output:

o* *r

Length

Length is the count of the symbols contained in a string.

It's accessed via the length function.

Example:

string word = "Hello!"; cout << word.length();

Output:

6

Via length() we can access the last symbol of a string.

Example:

string str = "The quick brown fox jumps over the lazy dog!"; cout << str[str.length() - 1];

Output:

!

Access outside of bounds

Accessing string outside of it's bounds results in exception.

Let's look the following example:

string str = "Phone"; str[10];

The string has indexes from 0 to 5 (5 is the '\0' symbol). Accessing index outside of that bound (in this case 10) causes exception.

Contains

We can check if string is contained in a string via the find function.

Examples:

#include <iostream> // So cin and cout can be used. #include <string> // Some compilers require this line for string usage. using namespace std; int main() { string str = "simple"; if (str.find("m") != string::npos) { cout << "m is contained in " << str << endl; } if (str.find("si") != string::npos) { cout << "si is contained in " << str << endl; } if (str.find("z") == string::npos) { cout << "z is not contained in " << str << endl; } if (str.find("S") != string::npos) { cout << "S is contained in " << str << endl; } }

Output:

m is contained in simple si is contained in simple z is not contained in simple

String iteration

All symbols of a string can be iterated via for loop.

Let's print all letters of a word that are not vowels:

#include <iostream> // So cin and cout can be used. #include <string> // Some compilers require this line for string usage. using namespace std; int main() { string word = "composure"; string vowels = "aeiou"; for (int i = 0; i < word.length(); i++) { char letter = word[i]; // if symbol is not contained in vowels if (vowels.find(letter) == string::npos) { cout << letter << " "; } } }

Output:

c m p s r

In this case vowels.find(letter) == string::npos means that letter is a symbol that's not a vowel letter.