Cadenas de C ++: uso de matriz de caracteres y objeto de cadena

En este artículo, aprenderá a manejar cadenas en C. Aprenderá a declararlas, inicializarlas y usarlas para varias operaciones de entrada / salida.

String es una colección de caracteres. Hay dos tipos de cadenas que se utilizan comúnmente en el lenguaje de programación C ++:

  • Cadenas que son objetos de la clase de cadena (la clase de cadena de la biblioteca estándar de C ++)
  • Cuerdas C (cuerdas estilo C)

Cuerdas C

En la programación C, la colección de caracteres se almacena en forma de matrices, esto también es compatible con la programación C ++. Por eso se llama C-strings.

Las cadenas C son matrices de tipo charterminado con carácter nulo, es decir, (el valor ASCII del carácter nulo es 0).

¿Cómo definir una cuerda C?

 char str () = "C ++";

En el código anterior, strhay una cadena y tiene 4 caracteres.

Aunque " C++" tiene 3 caracteres, el carácter nulo se agrega al final de la cadena automáticamente.

Formas alternativas de definir una cadena

char str (4) = "C ++"; char str () = ('C', '+', '+', ' 0'); char str (4) = ('C', '+', '+', ' 0');

Al igual que las matrices, no es necesario utilizar todo el espacio asignado para la cadena. Por ejemplo:

 char str (100) = "C ++";

Ejemplo 1: Cadena C ++ para leer una palabra

Programa C ++ para mostrar una cadena ingresada por el usuario.

 #include using namespace std; int main() ( char str(100); cout <> str; cout << "You entered: " << str << endl; cout <> str; cout << "You entered: "<

Output

 Enter a string: C++ You entered: C++ Enter another string: Programming is fun. You entered: Programming

Notice that, in the second example only "Programming" is displayed instead of "Programming is fun".

This is because the extraction operator>> works as scanf() in C and considers a space " " has a terminating character.

Example 2: C++ String to read a line of text

C++ program to read and display an entire line entered by user.

 #include using namespace std; int main() ( char str(100); cout << "Enter a string: "; cin.get(str, 100); cout << "You entered: " << str << endl; return 0; )

Output

 Enter a string: Programming is fun. You entered: Programming is fun.

To read the text containing blank space, cin.get function can be used. This function takes two arguments.

First argument is the name of the string (address of first element of string) and second argument is the maximum size of the array.

In the above program, str is the name of the string and 100 is the maximum size of the array.

string Object

In C++, you can also create a string object for holding strings.

Unlike using char arrays, string objects has no fixed length, and can be extended as per your requirement.

Example 3: C++ string using string data type

 #include using namespace std; int main() ( // Declaring a string object string str; cout << "Enter a string: "; getline(cin, str); cout << "You entered: " << str << endl; return 0; )

Output

 Enter a string: Programming is fun. You entered: Programming is fun.

In this program, a string str is declared. Then the string is asked from the user.

Instead of using cin>> or cin.get() function, you can get the entered line of text using getline().

getline() function takes the input stream as the first parameter which is cin and str as the location of the line to be stored.

Passing String to a Function

Strings are passed to a function in a similar way arrays are passed to a function.

 #include using namespace std; void display(char *); void display(string); int main() ( string str1; char str(100); cout << "Enter a string: "; getline(cin, str1); cout << "Enter another string: "; cin.get(str, 100, ''); display(str1); display(str); return 0; ) void display(char s()) ( cout << "Entered char array is: " << s << endl; ) void display(string s) ( cout << "Entered string is: " << s << endl; )

Output

 Enter a string: Programming is fun. Enter another string: Really? Entered string is: Programming is fun. Entered char array is: Really?

In the above program, two strings are asked to enter. These are stored in str and str1 respectively, where str is a char array and str1 is a string object.

Then, we have two functions display() that outputs the string onto the string.

The only difference between the two functions is the parameter. The first display() function takes char array as a parameter, while the second takes string as a parameter.

This process is known as function overloading. Learn more about Function Overloading.

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