C++ Programming Code Examples C++ > Conversions Code Examples Convert Hexadecimal to Octal Convert Hexadecimal to Octal To convert hexadecimal number to octal number in C++ programming, you have to ask to the user to enter the hexadecimal number to convert it into octal number to display the equivalent value in octal format as shown here in the following program. Following C++ program ask to the user to enter any number in Hexadecimal format to convert it into octal, then display the result on the screen: Here first we will convert the entered hexadecimal number into decimal number then we will convert it into octal number. That is, from hexadecimal to octal. #include<iostream.h> #include<conio.h> #include<string.h> #include<math.h> int hex_to_oct(char hex[]); void main() { clrscr(); char hex[20],c; int n; cout<<"Enter Hexadecimal Number : "; cin>>hex; cout<<"Equivalent Octal Value = %d",hex_to_oct(hex); getch(); } int hex_to_oct(char hex[]) { int i,len, dec=0, oct=0; for(len=0; hex[len]!='\0'; len++); for(i=0; hex[i]!='\0'; i++,len--) { if(hex[i]>='0' && hex[i]<='9') { dec= dec + (hex[i]-'0')*pow(16,len-1); } if(hex[i]>='A' && hex[i]<='F') { dec = dec + (hex[i]-55)*pow(16,len-1); } if(hex[i]>='a' && hex[i]<='f') { dec = dec + (hex[i]-87)*pow(16,len-1); } } /* Now dec contains the decimal value of given hexadecimal number. */ i=1; while(dec!=0) { oct = oct + (dec%8)*i; dec = dec/8; i = i*10; } return oct; }