C ++ stringid: char massiivi ja stringi objekti kasutamine

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Selles artiklis õpitakse stringe käsitsema kirjas C. Õpid neid deklareerima, initsialiseerima ja kasutama mitmesuguste sisend- / väljundoperatsioonide jaoks.

String on tähemärkide kogu. C ++ programmeerimiskeeles kasutatakse tavaliselt kahte tüüpi stringe:

  • Stringid, mis on stringiklassi objektid (standardne C ++ teegi stringiklass)
  • C-stringid (C-stiilis stringid)

C-stringid

C-programmeerimisel salvestatakse märkide kogu massiividena, seda toetab ka C ++ -programmeerimine. Seetõttu nimetatakse seda C-stringideks.

C-stringid on tüüpi massiivid char, mis on lõpetatud nullmärgiga, st (nullmärgi ASCII väärtus on 0).

Kuidas määratleda C-string?

 char str () = "C ++";

Ülalolevas koodis stron string ja see sisaldab 4 tähemärki.

Ehkki " C++" -il on 3 tähemärki, lisatakse nullmärk stringi lõppu automaatselt.

Stringi määratlemise alternatiivsed viisid

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

Nagu massiivid, ei ole ka stringi jaoks eraldatud ruumi vaja ära kasutada. Näiteks:

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

Näide 1: C ++ string sõna lugemiseks

C ++ programm kasutaja sisestatud stringi kuvamiseks.

 #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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