KAKO PRETVORITI NIZOVE C STILA U STD::STRING I OBRNUTO?

Što su Žice u stilu C ? Ovi nizovi su niz znakova koji završavaju znakom NULL. Nizovi u stilu C mogu se deklarirati na sljedeće načine:

Deklaracija i inicijalizacija

CPP

/* To demonstrate C style strings */ #include   using namespace std; int main() {  /* Null character has to be added explicitly */  char str1[8] = {'H'  'E'  'L'  'L'  'O'   '-''1''' };    /* Compiler implicitly adds Null character */  char str2[] = 'HELLO-2' ;     /* Compiler implicitly adds Null character.   Note that string literals are typically stored  as read only */  const char *str3 = 'HELLO-3' ;  cout << str1 << endl << str2 << endl << str3;  return 0; }

Output:

HELLO-1 HELLO-2 HELLO-3

C style strings are operated with very useful functions like strcpy() strlen() strpbrk() strach() strstr() i još mnogo toga! (Sve ove funkcije su funkcije članice ' cstring ' zaglavlje ). Što je std::string? C++ standardna biblioteka sadrži funkcije i klase. String je jedna od njegovih klasa. Ovdje imamo posla s objektom klase string. Ovaj std::string brine sam o sebi i upravlja vlastitom memorijom.

Deklaracija i inicijalizacija

CPP

/* To demonstrate std::string */ #include   #include  using namespace std; int main() {  /* s becomes object of class string. */  string s;   /* Initializing with a value. */   s = 'HELLO';  /* Printing the value */   cout << s;     return 0; }

Output:

HELLO

Pretvaranje C-stringa u std::string. Ali zašto nam je potrebna ova transformacija? Od C niza do std::stringa? To je zato što

Std::string upravlja vlastitim prostorom. Dakle, programer ne treba brinuti o memoriji za razliku od C nizova (budući da su niz znakova)
Jednostavni su za rukovanje. '+' operator za ulančavanje '=' za dodjelu može se usporediti korištenjem uobičajenih operatora.
Iteratori se mogu koristiti u std::string, a ne u C-stringovima.

And many more! Here is the code for it:- CPP

/* To demonstrate C style string to std::string */ #include   using namespace std; int main() {  /*Initializing a C-String */  const char *a = 'Testing';   cout << 'This is a C-String : '<< a << endl;  /* This is how std::string s is assigned  though a C string ‘a’ */  string s(a);     /* Now s is a std::string and a is a C-String */  cout << 'This is a std::string : '<< s << endl;  return 0; }

Output:

This is a C-String : Testing This is a std::string : Testing

The above conversion also works for character array.

 // Character array to std::string conversion char a[] = 'Testing'; string s(a);

Pretvaranje std::stringa u niz C stila Zašto nam je potrebna ova transformacija? Od std::string do C niza?

To je zato što postoji nekoliko moćnih funkcija u zaglavlju koje nam uvelike olakšavaju rad.

gušiti()

You can think of other reasons too! Here is the code for conversion:- CPP

/* To demonstrate std::string to C style string */ #include   #include /* This header contains string class */ using namespace std; int main() {  /* std::string initialized */  string s = 'Testing';   cout << 'This is a std::string : '<< s << endl;  /* Address of first character of std::string is   stored to char pointer a */  char *a = &(s[0]);   /* Now 'a' has address of starting character  of string */  printf('%sn' a);   return 0; }

Output:

This is a std::string : Testing This is a C-String : Testing

std::string also has a function c_str() that can be used to get a null terminated character array. CPP

/* To demonstrate std::string to C style string using  c_str() */ #include   using namespace std; int main() {  /* std::string initialized */  string s = 'Testing';   cout << 'This is a std::string : '<< s << endl;  // c_str returns null terminated array of characters  const char *a = s.c_str();  /* Now 'a' has address of starting character  of string */  printf('%sn' a);   return 0; }

Output:

This is a std::string : Testing This is a C-String : Testing

Both C strings and std::strings have their own advantages. One should know conversion between them to solve problems easily and effectively. Povezani članci: Klasa nizova C++ i njezine primjene | Set 1 Klasa nizova C++ i njezine primjene | Set 2

TechCodeview

Kako pretvoriti nizove C stila u std::string i obrnuto?