C++ Program to Generate Random Hexadecimal Bytes

We shall discuss about a C++ program which can generate random Hexadecimal numbers. Here we shall use rand() and itoa() functions to implement the same. Let us discuss on these functions separately and categorically.

rand(): rand() function is a predefined method of C++. It is declared in <stdlib.h> header file. rand() is used to generate random number within a range. Here min_n is the minimum range of the random numbers and max_n is the maximum range of the numbers. So rand() will return the random numbers between min_n to (max_n – 1) inclusive of the limit values. Here if we mention lower and upper limits as 1 and 100 respectively, then rand() will return values from 1 to (100 – 1). i.e. from 1 to 99.

itoa(): It returns the converted value of a decimal or integer number. It converts the value to a null-terminated string with a specified base. It stores the converted value to a user defined array.


itoa(new_n, Hexadec_n, 16);

Here new_n is any random integer number and Hexadec_n is the user defined array and 16 is the base of hexadecimal number. That means in converts a decimal or integer number to hexadecimal number.


   Declare max_n to the integer datatype.
      Initialize max_n = 100.
   Declare min_n to the integer datatype.
      Initialize min_n = 1.
   Declare an array Hexadec_n to the character datatype.
   Declare new_n to the integer datatype.
   Declare i to the integer datatype.
   for (i = 0; i < 5; i++)
      new_n = ((rand() % (max_n + 1 - min_n)) + min_n)
      Print “The random number is:”.
      Print the value of new_n.
      Call itoa(new_n, Hexadec_n, 16) method to
      convert a random decimal number to hexadecimal number.
      Print “Equivalent Hex Byte:”
         Print the value of Hexadec_n.


using namespace std;
int main(int argc, char **argv) {
   int max_n = 100;
   int min_n = 1;
   char Hexadec_n[100];
   int new_n;
   int i;
   for (i = 0; i < 5; i++) {
      new_n = ((rand() % (max_n + 1 - min_n)) + min_n);
      //rand() returns random decimal number.
      cout<<"The random number is: "<<new_n;
      itoa(new_n, Hexadec_n, 16); //converts decimal number to Hexadecimal number.
      cout << "\nEquivalent Hex Byte: "
   return 0;


The random number is: 42
Equivalent Hex Byte: 2a
The random number is: 68
Equivalent Hex Byte: 44
The random number is: 35
Equivalent Hex Byte: 23
The random number is: 1
Equivalent Hex Byte: 1
The random number is: 70
Equivalent Hex Byte: 46

Updated on: 30-Jul-2019


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