KAKO PRETVORITI NIZE V SLOGU C V STD::STRING IN OBRATNO?

Kaj so Strune v slogu C ? Ti nizi so nizi znakov, ki se končajo z znakom NULL. Nize v slogu C je mogoče deklarirati na naslednje načine:

Deklaracija in inicializacija

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() in še veliko več! (Vse te funkcije so članske funkcije ' cstring ' glava ). Kaj je std::string? Standardna knjižnica C++ vsebuje funkcije in razrede. Niz je eden od njegovih razredov. Tukaj imamo opravka z objektom razreda nizov. Ta std::string skrbi zase in upravlja lasten pomnilnik.

Deklaracija in inicializacija

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

Pretvarjanje C-niza v std::string. Toda zakaj potrebujemo to preobrazbo? Iz niza C v std::string? To je zato, ker

Std::string upravlja svoj prostor. Programerju torej ni treba skrbeti za pomnilnik za razliko od nizov C (ker so niz znakov)
Z njimi je enostavno upravljati. Operator '+' za veriženje '=' za dodelitev je mogoče primerjati z običajnimi operatorji.
Iteratorje je mogoče uporabiti v std::string in ne v nizih C.

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);

Pretvorba std::string v niz v slogu C Zakaj potrebujemo to preobrazbo? Iz std::string v niz C?

Ker je v glavi več zmogljivih funkcij, nam delo zelo olajša.

duši ()

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. Sorodni članki: Razred nizov C++ in njegove aplikacije | Komplet 1 Razred nizov C++ in njegove aplikacije | Komplet 2

TechCodeview

Kako pretvoriti nize v slogu C v std::string in obratno?