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We will write a C++ program to check whether a character is an alphabet or not. Before that, you should have knowledge of the following in C++.

• C++ if..else statement

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Program to Check Alphabet or Not in C++

First of all the program ask the user to enter a character that needed to be checked and then starts the process of checking.

Using if-else statement if checks whether entered character is greater than or equals to a and less than or equal to z or not. Along with that, using or operator (||) another condition is checked for the uppercase alphabet that is whether entered character is greater than or equals to A and less than or equal to Z or not.

If either of the condition is true then if the part is executed otherwise else part is executed. The program is checking for both lowercase alphabet and uppercase alphabet.

#include <iostream>
using namespace std;

int main()
{
   char ch;

   cout << "Enter a Character: ";
   cin >> ch;

   if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))
      cout << ch << " is an Alphabet";
   else
      cout << ch << " is NOT an Alphabet";

   return 0;
}

Output:

//Run 1
Enter a Character: A
A is an Alphabet

//Run 2
Enter a Character: 5
5 is NOT an Alphabet

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Using ASCII Value

We will do the same except we will compare the character with ASCII value.

• The ASCII values for lowercase characters ranges between 67 to 122. (‘a’ = 97 and ‘z’ = 122).
• The ASCII values for uppercase characters ranges between 65 to 92. (‘A’ = 65 and ‘Z’ = 90).

C++ program to check whether the entered character is alphabet or not using ASCII value.

#include <iostream>
using namespace std;

int main()
{
   char ch;

   cout << "Enter a Character: ";
   cin >> ch;

   if ((ch >= 65 && ch <= 90) || (ch >= 97 && ch <= 122))
      cout << ch << " is an Alphabet";
   else
      cout << ch << " is NOT an Alphabet";

   return 0;
}

After executing this program, it will produce the same result as the first program mentioned above.

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In this simple tutorial, we will learn to get input from the user in C++. We will learn to take integer, character, string with spaces as an input. If you want to learn about the data types in C++ then go through the following tutorial.

• C++ data types
• C++ String

Take Integer and Character as an Input from User

The program is simple, to take an input we use cin input stream present in C++. The program asks the user to enter an integer and displays that value on the screen. Then it also asks the user to enter a character and the value is again printed on the screen.

#include <iostream>
using namespace std;

int main()
{
  	// integer
   int val;
   cout << "Enter the Number: ";
   cin >> val;

   cout << "Integer Value " << val;

  	// Character
   char ch;
   cout << "\n\nEnter a Character: ";
   cin >> ch;
   cout << "Character value: " << ch;

   return 0;
}

Output:

Enter the Number: 25
Integer Value 25

Enter a Character: A
Character value: A

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Get String Input with Spaces

We can get a string with spaces from the user with the use of gets() function or getline() function. Use them in the following way in the program.

gets(str);

getline(cin, str);

1. Take String input with Spaces using gets()

#include <iostream>
#include <stdio.h>
using namespace std;

int main()
{
   char str[200];

   cout << "Enter the String: ";
   gets(str);

   cout << "String entered: " << str;

   return 0;
}

Enter the String: This is simple2code.com
String entered: This is simple2code.com

2. Take String Input with Spaces using getline()

#include <iostream>
#include <string>
using namespace std;

int main()
{
   string str;

   cout << "Enter the String: ";
   getline(cin, str);

   cout << "String entered: " << str;

   return 0;
}

Enter the String: I am simple2code.com
String entered: I am simple2code.com

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In this tutorial, we will write a program to convert an octal number into hexadecimal in C++. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop
• C++ for loop

Hexadecimal number

The hexadecimal number is represented with a base of 16. It has digits from 0 to 15 to represent, However after 9 the values are represented in Alphabet till 15 such as 10 is represented as A, 11 as B, 12 as C, 13 as D, 14 as E, and 15 as F.

Octal number

The octal numbers are the numbers with base 8 and use the digits 0 to 7. Example: 8 in decimal is represented as 10 in octal, 25 as 31, and so on.

Let us go through a program for the Octal to Hexadecimal Conversion in C++.

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C++ Program to Convert Octal to Hexadecimal

#include <iostream>
#include <string.h>
#include <math.h>
using namespace std;

int main()
{
   char octalNumber[20];
   int arr1[20], arr2[20], rev[20];
   int h, i, j, k, l, x, fr, flag, rem, n1, n3;
   float rem1, n2, n4, dno;

   x = fr = flag = rem = 0;
   rem1 = 0.0;

   cout << "Enter an Octal number: ";
   cin >> octalNumber;

   for (i = 0, j = 0, k = 0; i < strlen(octalNumber); i++)
   {
      if (octalNumber[i] == '.')
         flag = 1;
      else if (flag == 0)
         arr1[j++] = octalNumber[i] - 48;
      else if (flag == 1)
         arr2[k++] = octalNumber[i] - 48;
   }

   x = j;
   fr = k;

   for (j = 0, i = x - 1; j < x; j++, i--)
   {
      rem = rem + (arr1[j] *pow(8, i));
   }

   for (k = 0, i = 1; k < fr; k++, i++)
   {
      rem1 = rem1 + (arr2[k] / pow(8, i));
   }

   rem1 = rem + rem1;
   dno = rem1;
   n1 = (int) dno;
   n2 = dno - n1;

   i = 0;
   while (n1 != 0)
   {
      rem = n1 % 16;
      rev[i] = rem;
      n1 = n1 / 16;
      i++;
   }

   j = 0;
   while (n2 != 0.0)
   {
      n2 = n2 * 16;
      n3 = (int) n2;
      n4 = n2 - n3;
      n2 = n4;
      arr1[j] = n3;
      j++;

      if (j == 4)
         break;
   }

   l = i;
   cout << "Equivalent hexadecimal value: ";
   for (i = l - 1; i >= 0; i--)
   {
      if (rev[i] == 10)
         cout << "A";
      else if (rev[i] == 11)
         cout << "B";
      else if (rev[i] == 12)
         cout << "C";
      else if (rev[i] == 13)
         cout << "D";
      else if (rev[i] == 14)
         cout << "E";
      else if (rev[i] == 15)
         cout << "F";
      else
         cout << rev[i];
   }
}

Output:

Enter an Octal number: 377
Equivalent hexadecimal value: FF

The above program calculates the natural part of the octal number. If you also want the program the decimal octal number to decimal hexadecimal number then add the following code after the end of the last for loop on the above program.

h = j;
cout << ".";
for (k = 0; k < h; k++)
{
   if (arr1[k] == 10)
      cout << "A";
   else if (arr1[k] == 11)
      cout << "B";
   else if (arr1[k] == 12)
      cout << "C";
   else if (arr1[k] == 13)
      cout << "D";
   else if (arr1[k] == 14)
      cout << "E";
   else if (arr1[k] == 15)
      cout << "F";
   else
      cout << arr1[k];
}

Then you will get output something like this,

Enter an Octal number: 137.6
Equivalent hexadecimal value: 5F.C

You may go through the vice-versa program:

• C++ Program to Convert Hexadecimal to Octal

---

In this tutorial, we will write a program to convert a hexadecimal number into octal in C++. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop
• C++ for loop

Hexadecimal number

The hexadecimal number is represented with a base of 16. It has digits from 0 to 15 to represent, However after 9 the values are represented in Alphabet till 15 such as 10 is represented as A, 11 as B, 12 as C, 13 as D, 14 as E, and 15 as F.

Octal number

The octal numbers are the numbers with base 8 and use the digits 0 to 7. Example: 8 in decimal is represented as 10 in octal, 25 as 31, and so on.

Let us go through a program for the Hexadecimal to Octal Conversion in C++.

---

C++ Program to Convert Hexadecimal to Octal

#include <iostream>
#include <math.h>
using namespace std;

int main()
{
   int deci = 0, oct[30], rem, i = 0, length = 0;
   char hexDec[10];

   cout << "Enter a Hexadecimal Number: ";
   cin >> hexDec;

   //find the length of the number entered
   while (hexDec[i] != '\0')
   {
      length++;
      i++;
   }

   length--;

   i = 0;
   while (length >= 0)
   {
      rem = hexDec[length];

      if (rem >= 48 && rem <= 57)
         rem -= 48;
      else if (rem >= 65 && rem <= 70)
         rem -= 55;
      else if (rem >= 97 && rem <= 102)
         rem -= 87;
      else
      {
         cout << "The hexadecimal number entered is invalid.";
         return 0;  //exit the program
      }

      deci += (rem* pow(16, i));
      length--;
      i++;
   }

   i = 0;
   while (deci != 0)
   {
      oct[i] = deci % 8;
      i++;
      deci /= 8;
   }

   //display
   cout << "Equivalent Octal Value: ";
   for (i = i - 1; i >= 0; i--)
      cout << oct[i];

   return 0;
}

Output:

//Run 1
Enter a Hexadecimal Number: 5F
Equivalent Octal Value: 137

//Run 2
Enter a Hexadecimal Number: 2HD
The hexadecimal number entered is invalid.

You may go through the vice-versa program:

• C++ Convert Octal to Hexadecimal

---

This is a C++ Program to Convert a HexadecimalNumber to its Binary Equivalent. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop

Binary number

The binary numbers are based on 0 and 1, so it is a base 2 number. They are the combination of 0 and 1. For example, 1001, 110101, etc.

Hexadecimal number

The hexadecimal number is represented with a base of 16. It has digits from 0 to 15 to represent, However after 9 the values are represented in Alphabet till 15 such as 10 is represented as A, 11 as B, 12 as C, 13 as D, 14 as E, and 15 as F.

Now let us go through a program for hexadecimal to Binary conversion in C++.

---

C++ Program to Convert Hexadecimal to Binary

#include<iostream>
using namespace std;

void conversionFunc(string);

//main function
int main()
{
    string hexDeci;
    
    cout << "Enter the Hexadecimal Number: ";
    cin >> hexDeci;
    
   cout << "Equivalent Binary value: " ;
   conversionFunc(hexDeci);
   
   return 0;
}

//user-defined function
void conversionFunc(string hexDeci)
{
    int i = 0;
    
   while (hexDeci[i])
   {
      switch (hexDeci[i])
      {
      case '0':
         cout << "0000";
         break;
      case '1':
         cout << "0001";
         break;
      case '2':
         cout << "0010";
         break;
      case '3':
         cout << "0011";
         break;
      case '4':
         cout << "0100";
         break;
      case '5':
         cout << "0101";
         break;
      case '6':
         cout << "0110";
         break;
      case '7':
         cout << "0111";
         break;
      case '8':
         cout << "1000";
         break;
      case '9':
         cout << "1001";
         break;
      case 'A':
      case 'a':
         cout << "1010";
         break;
      case 'B':
      case 'b':
         cout << "1011";
         break;
      case 'C':
      case 'c':
         cout << "1100";
         break;
      case 'D':
      case 'd':
         cout << "1101";
         break;
      case 'E':
      case 'e':
         cout << "1110";
         break;
      case 'F':
      case 'f':
         cout << "1111";
         break;
      default:
         cout << "Invalid HexaDecimal Number----"<< hexDeci[i];
      }
   i++;
   }
}

Output:

//Run 1
Enter the Hexadecimal Number: A
Equivalent Binary value: 1010

//Run 2
Enter the Hexadecimal Number: 2A
Equivalent Binary value: 00101010

You may go through the vice-versa program:

• C++ Program to Convert Binary to Hexadecimal

---

This is a C++ Program to Convert a Binary Number to its Hexadecimal Equivalent. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop

Binary number

The binary numbers are based on 0 and 1, so it is a base 2 number. They are the combination of 0 and 1. For example, 1001, 110101, etc.

Hexadecimal number

The hexadecimal number is represented with a base of 16. It has digits from 0 to 15 to represent, However after 9 the values are represented in Alphabet till 15 such as 10 is represented as A, 11 as B, 12 as C, 13 as D, 14 as E, and 15 as F.

Now let us go through a program for Binary to hexadecimal conversion in C++.

---

C++ Program to Convert Binary to Hexadecimal

#include <iostream>
#include <math.h>
using namespace std;

int main()
{
   int hexNumber[100];
   int i = 1, j = 0, rem, dec = 0, binNumber;

   cout << "Enter a Binary number: ";
   cin >> binNumber;

   while (binNumber > 0)
   {
      rem = binNumber % 2;
      dec = dec + rem * i;
      i = i * 2;
      binNumber = binNumber / 10;
   }

   i = 0;

   while (dec != 0)
   {
      hexNumber[i] = dec % 16;
      dec = dec / 16;
      i++;
   }

   cout << "Equivalent Hexadecimal value: ";
   for (j = i - 1; j >= 0; j--)
   {
      if (hexNumber[j] > 9)
      {
         cout << (char)(hexNumber[j] + 55);
      }
      else
      {
         cout << hexNumber[j];
      }
   }
}

Output:

Enter a Binary number: 11111
Equivalent Hexadecimal value: 1F

You may go through the vice-versa program:

• C++ Convert Hexadecimal to Binary

---

In this tutorial, we will write a C++ program to convert a binary number into octal using while loop. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop

Binary number

The binary numbers are based on 0 and 1, so it is a base 2 number. They are the combination of 0 and 1. For example, 1001, 110101, etc.

Octal number

The octal numbers are the numbers with base 8 and use the digits 0 to 7. Example: 8 in decimal is represented as 10 in octal, 25 as 31, and so on.

Let us go through a program for the Binary to Octal Conversion in C++.

---

C++ Program to Convert Binary to Octal

#include <iostream>
#include <cmath>
using namespace std;

//user defined function
int conversionFunc(int binNumber)
{
   int octNumber = 0, deciNum = 0, i = 0;

   while (binNumber != 0)
   {
      deciNum += (binNumber % 10) *pow(2, i);
      ++i;
      binNumber /= 10;
   }

   i = 1;

   while (deciNum != 0)
   {
      octNumber += (deciNum % 8) *i;
      deciNum /= 8;
      i *= 10;
   }

   return octNumber;
}

// MAIN Function
int main()
{
   int binNumber, result;

   cout << "Enter a binary number: ";
   cin >> binNumber;

   result = conversionFunc(binNumber);
   cout << "Equivalent Octal value: " << result;

   return 0;
}

Output:

Enter a binary number: 1101110
Equivalent Octal value: 156

You may go through the vice versa conversion:

• C++ Convert Octal to Binary

---

In this tutorial, we will write a program to convert an octal number into binary in C++. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop

Binary number

The binary numbers are based on 0 and 1, so it is a base 2 number. They are the combination of 0 and 1. For example, 1001, 110101, etc.

Octal number

The octal numbers are the numbers with base 8 and use the digits 0 to 7. Example: 8 in decimal is represented as 10 in octal, 25 as 31, and so on.

Let us go through a program for the Octal to Binary Conversion in C++.

---

C++ Program to Convert Octal to Binary

#include <iostream>
#include <cmath>
using namespace std;

//user defined function
int conversionFunc(int octNumber)
{
   int deciNum = 0, binNumber = 0, i = 0;

   while (octNumber != 0)
   {
      deciNum += (octNumber % 10) *pow(8, i);
      ++i;
      octNumber /= 10;
   }

   i = 1;

   while (deciNum != 0)
   {
      binNumber += (deciNum % 2) *i;
      deciNum /= 2;
      i *= 10;
   }

   return binNumber;
}

//Main function
int main()
{
   int octNumber, result;

   cout << "Enter an octal number: ";
   cin >> octNumber;

   result = conversionFunc(octNumber);
   cout << "Equivalent Binary Number: " << result;

   return 0;
}

Output:

Enter an octal number: 64
Equivalent Binary Number: 110100

You may go through the vice versa conversion:

• C++ Convert Binary to Octal

---

This is a C++ Program to Convert a Hexadecimal Number to its decimal Equivalent. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop
• C++ if..elseif

Hexadecimal number

The hexadecimal number is represented with a base of 16. It has digits from 0 to 15 to represent, However after 9 the values are represented in Alphabet till 15 such as 10 is represented as A, 11 as B, 12 as C, 13 as D, 14 as E, and 15 as F.

Decimal Number

These are the numbers with a base of 10, which ranges from 0 to 9. These numbers are formed with the combination of 0 to 9 digits such as 24, 345, etc.

Now let us go through a program for Hexadecimal to decimal conversion in C++.

---

C++ Program to Convert Hexadecimal to Decimal

#include <iostream>
#include <math.h>
using namespace std;

int main()
{
   char hexDeci[20];
   int deci = 0, rem, i = 0, len = 0;

   cout << "Enter the Hexadecimal Number: ";
   cin >> hexDeci;

   //calculating the length of hexa entered
   while (hexDeci[i] != '\0')
   {
      len++;
      i++;
   }

   len--;
   i = 0;

   while (len >= 0)
   {
      rem = hexDeci[len];

      if (rem >= 48 && rem <= 57)
         rem = rem - 48;
      else if (rem >= 65 && rem <= 70)
         rem = rem - 55;
      else if (rem >= 97 && rem <= 102)
         rem = rem - 87;
      else
      {
         cout << "The entered hexa digit is invalid";
         return 0; //exit the program
      }

      deci += (rem* pow(16, i));
      len--;
      i++;
   }

   //Display
   cout << "Decimal Value: " << deci;

   return 0;
}

Output:

//Run 1
Enter the Hexadecimal Number: 119E
Decimal Value: 4510

//Run 2
Enter the Hexadecimal Number: 45H
The entered hexa digit is invalid

Also, here we have used a while loop to calculate the length of the hexadecimal number entered. However, you can use strlen() function to calculate the length. Remember to include string.h header file before using this string function.

You may go through the following vice versa program:

• C++ Program to Convert Decimal to Hexadecimal

---

This is a C++ Program to Convert a Decimal Number to its HexaDecimal Equivalent. Before that, you must have knowledge of the following topics in C++.

• C++ operator
• C++ while loop

Hexadecimal number

The hexadecimal number is represented with a base of 16. It has digits from 0 to 15 to represent, However after 9 the values are represented in Alphabet till 15 such as 10 is represented as A, 11 as B, 12 as C, 13 as D, 14 as E, and 15 as F.

Decimal Number

These are the numbers with a base of 10, which ranges from 0 to 9. These numbers are formed with the combination of 0 to 9 digits such as 24, 345, etc.

Now let us go through a program for decimal to hexadecimal conversion in C++.

---

C++ Program to Convert Decimal to Hexadecimal

The programs ask the user to enter a decimal number and iterating the number with the help of a while loop, the program calculates the equivalent hexadecimal value.

#include <iostream>
using namespace std;

int main()
{
   char hexaDeci[50];
   int deci, rem, i = 0;

   cout << "Enter the Decimal Number: ";
   cin >> deci;

   while (deci != 0)
   {
      rem = deci % 16;
      if (rem < 10)
         rem = rem + 48;
      else
         rem = rem + 55;

      hexaDeci[i] = rem;
      i++;
      deci = deci / 16;
   }

   //Display
   cout << "Hexadecimal value: ";
   for (i = i - 1; i >= 0; i--)
      cout << hexaDeci[i];

   return 0;
}

Output:

Enter the Decimal Number: 4510
Hexadecimal value: 119E

You may go through the following vice versa program:

• C++ Convert Hexadecimal to Decimal

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