How to use use an array of pointers (Jagged) in C/C++?

Let us consider the following example, which uses an array of 3 integers −

In C

Example

#include <stdio.h>
const int MAX = 3;
int main () {
   int var[] = {10, 100, 200};
   int i;
   for (i = 0; i < MAX; i++) {
      printf("Value of var[%d] = %d\n", i, var[i] );
   }
   return 0;
}

Output

Value of var[0] = 10
Value of var[1] = 100
Value of var[2] = 200

In C++

Example

#include <iostream>
using namespace std;
const int MAX = 3;
int main () {
   int var[] = {10, 100, 200};
   int i;
   for (i = 0; i < MAX; i++) {
      cout<<"Value of var"<<i<<"="<<var[i]<<"\n";
   }
   return 0;
}

Output

Value of var0=10
Value of var1=100
Value of var2=200

There may be a situation when we want to maintain an array, which can store pointers to an int or char or any other data type available. Following is the declaration of an array of pointers to an integer −

int *ptr[MAX]

It declares ptr as an array of MAX integer pointers. Thus, each element in ptr, holds a pointer to an int value. The following example uses three integers, which are stored in an array of pointers, as follows −

In C

Example

#include <stdio.h>
const int MAX = 3;
int main () {
   int var[] = {10, 100, 200};
   int i, *ptr[MAX];
   for ( i = 0; i < MAX; i++) {
      ptr[i] = &var[i]; /* assign the address of integer. */
   }
   for ( i = 0; i < MAX; i++) {
      printf("Value of var[%d] = %d\n", i, *ptr[i] );
   }
   return 0;
}

Output

Value of var[0] = 10
Value of var[1] = 100
Value of var[2] = 200

In C++

Example

#include <iostream>
using namespace std;
const int MAX=3;
int main () {
   int var[] = {10, 100, 200};
   int i, *ptr[MAX];
   for ( i = 0; i < MAX; i++) {
      ptr[i] = &var[i]; /* assign the address of integer. */
   }
   for ( i = 0; i < MAX; i++) {
      cout<<"Value of var" << i<<"="<<*ptr[i] <<"\n";
   }
}

Output

Value of var0=10
Value of var1=100
Value of var2=200

You can also use an array of pointers to character to store a list of strings as follows −

In C

Example

#include <stdio.h>
const int MAX = 4;
int main () {
   char *names[] = {
      "Zara Ali",
      "Hina Ali",
      "Nuha Ali",
      "Sara Ali"
   };
   int i = 0;
   for ( i = 0; i < MAX; i++) {
      printf("Value of names[%d] = %s\n", i, names[i] );
   }
   return 0;
}

Output

Value of names[0] = Zara Ali
Value of names[1] = Hina Ali
Value of names[2] = Nuha Ali
Value of names[3] = Sara Ali

In C++

Example

#include <iostream>
using namespace std;
const int MAX=4;
int main () {
   char *names[] = {
      "Zara Ali",
      "Hina Ali",
      "Nuha Ali",
      "Sara Ali"
   };
   int i = 0;
   for ( i = 0; i < MAX; i++) {
      cout<<"Value of names"<< i<<"="<< names[i]<<"\n";
   }
   return 0;
}

Output

Value of names0=Zara Ali
Value of names1=Hina Ali
Value of names2=Nuha Ali
Value of names3=Sara Ali