C++ Tutorial/Array/array pointer

Материал из C\C++ эксперт
Перейти к: навигация, поиск

an array of pointers to strings

#include <iostream>  
  using namespace std;  
  const int DAYS = 7;            
    
  int main(){                           
     char* arrptrs[DAYS] = { "Sunday", "Monday", "Tuesday",  
                             "Wednesday", "Thursday",  
                             "Friday", "Saturday"  };  
    
     for(int j=0; j<DAYS; j++)
        cout << arrptrs[j] << endl;  
     return 0;  
  }

array accessed with array notation

#include <iostream>  
  using namespace std;  
    
  int main(){
     int intarray[5] = { 31, 54, 77, 52, 93 };  
    
     for(int j=0; j<5; j++)  
        cout << intarray[j] << endl;
     return 0;  
  }

array accessed with pointer

#include <iostream>  
  using namespace std;  
    
  int main(){  
     int intarray[] = { 31, 54, 77, 52, 93 }; 
     int* ptrint;                             
     ptrint = intarray;                       
    
     for(int j=0; j<5; j++)                     
        cout << *(ptrint++) << endl;          
     return 0;  
  }

array accessed with pointer notation

#include <iostream>  
  using namespace std;  
    
  int main(){
     int intarray[5] = { 31, 54, 77, 52, 93 };  
    
     for(int j=0; j<5; j++) 
        cout << *(intarray+j) << endl; 
     return 0;  
    }

Array pointer

#include <iostream> 
using namespace std; 
 
int main() 
{ 
  int *i, j[10]; 
  double *f, g[10]; 
  int x; 
 
  i = j;  
  f = g;  
 
  for(x=0; x<10; x++)  
    cout << i+x << " " << f+x << "\n";     
 
  return 0; 
}
0x22ff30 0x22fed0
0x22ff34 0x22fed8
0x22ff38 0x22fee0
0x22ff3c 0x22fee8
0x22ff40 0x22fef0
0x22ff44 0x22fef8
0x22ff48 0x22ff00
0x22ff4c 0x22ff08
0x22ff50 0x22ff10
0x22ff54 0x22ff18

Index a pointer as if it were an array

#include <iostream> 
#include <cctype> 
using namespace std; 
 
int main() 
{ 
  char *p; 
  int i; 
  char str[80] = "This Is A Test"; 
 
  cout << "Original string: " << str << "\n"; 
 
  p = str;
 
  for(i = 0; p[i]; i++) { 
    if(isupper(p[i])) 
      p[i] = tolower(p[i]); 
    else if(islower(p[i])) 
      p[i] = toupper(p[i]); 
  } 
 
  cout << "Inverted-case string: " << str; 
 
  return 0; 
}
Original string: This Is A Test
Inverted-case string: tHIS iS a tEST

Output array address by using array pointer

#include <assert.h>
#include <iostream>
#include <iomanip>
char array[10] = "012345678";
int main()
{
    for (int i = 0; i < 10; ++i) {
        std::cout << std::hex;
        std::cout << "&array[i]=0x" <<  reinterpret_cast<int>(&array[i]) <<
                     " (array+i)=0x" << reinterpret_cast<int>(array+i) <<
                     " array[i]=0x" <<  static_cast<int>(array[i]) << "\n",
        std::cout << std::dec;
    }
    return (0);
}
&array[i]=0x43d000 (array+i)=0x43d000 array[i]=0x30
&array[i]=0x43d001 (array+i)=0x43d001 array[i]=0x31
&array[i]=0x43d002 (array+i)=0x43d002 array[i]=0x32
&array[i]=0x43d003 (array+i)=0x43d003 array[i]=0x33
&array[i]=0x43d004 (array+i)=0x43d004 array[i]=0x34
&array[i]=0x43d005 (array+i)=0x43d005 array[i]=0x35
&array[i]=0x43d006 (array+i)=0x43d006 array[i]=0x36
&array[i]=0x43d007 (array+i)=0x43d007 array[i]=0x37
&array[i]=0x43d008 (array+i)=0x43d008 array[i]=0x38
&array[i]=0x43d009 (array+i)=0x43d009 array[i]=0x0

passing array as a constant pointer

#include <iostream>
using namespace std;
void increase(int* const array, const int NUM_ELEMENTS);
void display(const int* const array, const int NUM_ELEMENTS);
int main()
{
    const int NUM_SCORES = 3;
    int highScores[NUM_SCORES] = {5, 3, 2};
    cout << "passing array as a constant pointer.\n\n";
    increase(highScores, NUM_SCORES);
    cout << "passing array as a constant pointer to a constant.\n";
    display(highScores, NUM_SCORES);
    return 0;
}
void increase(int* const array, const int NUM_ELEMENTS)
{
    for (int i = 0; i < NUM_ELEMENTS; ++i)
        array[i] += 500;
}
void display(const int* const array, const int NUM_ELEMENTS)
{
    for (int i = 0; i < NUM_ELEMENTS; ++i)
        cout << array[i] << endl;
}

Relationship between pointers and arrays

#include <iostream>
using namespace std;
void increase(int* const array, const int NUM_ELEMENTS);
void display(const int* const array, const int NUM_ELEMENTS);
int main()
{
    const int NUM_SCORES = 3;
    int highScores[NUM_SCORES] = {5, 3, 2};
    cout << "using array name as a constant pointer.\n";
    cout << *highScores << endl;
    cout << *(highScores + 1) << endl;
    cout << *(highScores + 2) << "\n\n";
    cout << "passing array as a constant pointer.\n\n";
    increase(highScores, NUM_SCORES);
    cout << "passing array as a constant pointer to a constant.\n";
    display(highScores, NUM_SCORES);
    return 0;
}
void increase(int* const array, const int NUM_ELEMENTS)
{
    for (int i = 0; i < NUM_ELEMENTS; ++i)
        array[i] += 500;
}
void display(const int* const array, const int NUM_ELEMENTS)
{
    for (int i = 0; i < NUM_ELEMENTS; ++i)
        cout << array[i] << endl;
}

Use a 2-D array of pointers to create a dictionary

#include <iostream> 
#include <cstring> 
using namespace std; 
  
int main() { 
 
  char *dictionary[][2] = { 
    "A", "AA", 
    "B", "BB", 
    "C", "CC", 
    "D", "DD", 
    "E", "EE", 
    "", "" 
  }; 
  char word[80]; 
  int i; 
 
  cout << "Enter word: "; 
  cin >> word; 
 
  for(i = 0; *dictionary[i][0]; i++) { 
    if(!strcmp(dictionary[i][0], word)) { 
      cout << dictionary[i][1] << "\n"; 
      break; 
    } 
  } 
 
  if(!*dictionary[i][0]) 
    cout << word << " not found.\n"; 
 
  return 0; 
}
Enter word: word
word not found.
Источник — «http://cppe.ru/index.php?title=C%2B%2B_Tutorial/Array/array_pointer&oldid=2909»