converting a hex number to decimal???

This is a discussion on converting a hex number to decimal??? within the Game Programming forums, part of the General Programming Boards category; Does anyone know any quick way to convert a hex number to a decimal...

  1. #1
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    Question converting a hex number to decimal???

    Does anyone know any quick way to convert a hex number to a decimal

  2. #2
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    use a char array

    Code:
    char hex[9];
    inthex[9];
    cout<<"Enter hex  : ";
    cin.getline(hex,8,'\n');
    compare the input and write the corresponding number in an int array, use switch-case to compare and for to traverse the array
    Code:
    for(i=0;i<8;i++)
     switch(hex[i])
     {
      case 1:
        inthex[i]=1;
      break;
      case A:
       inthex[i]=10;
      :
      :
     }
    do the hex to dec calculations



    PS this is just some basic steps not actual code stuff, if it doesn't work post again... or do a search i think it has been asked before
    Last edited by ihsir; 04-09-2002 at 12:39 AM.
    -

  3. #3
    Registered User xds4lx's Avatar
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    This isnt that hard, heres a simple solution, store the hex representation as a string ex: "7AE". The way you convert to dec is go through a loop examining each character then you multiply the value in that index by 16^index. Oh yeah if you do it this way make sure you flip the string around since you convert from the right to left. ex:
    Code:
    int Hex_to_Dec(string strVal)
    {   int Val = 0;
        ReverseString(strVal); // you have to write this urself i just did this by pass by reference so i could modify the string in the function
    
        for(int cIndex = 0; cIndex < strVal.length(); cIndex++)
        {  char chVal = strVal[i];
           if((chVal > '0' || chVal < '9'))
           {	 Val += pow(HEX,cIndex) * atoi(Val);
           }
           else
           {   switch(chVal)
    	  {	case 'a':
    		case 'A':
    		{	Val+= pow(HEX,cIndex) * 10;
    			break;
    		}  
    		case 'b':
    		case 'B':
    		{	Val+= pow(HEX,cIndex) * 11;
    			break;
    		}
    		case 'c':
    		case 'C':
    		{	Val+= pow(HEX,cIndex) * 12;
    			break;
    		}
    		case 'd':
    		case 'D':
    		{	Val+= pow(HEX,cIndex) * 13;
    			break;
    		}
    		case 'e':
    		case 'E':
    		{	Val+= pow(HEX,cIndex) * 14;
    			break;
    		}
    		case 'f':
    		case 'F':
    		{	Val+= pow(HEX,cIndex) * 15;
    			break;
    		}
                  } // end of switch
              } // end of else
          } // end of for
          return(Val);
    }
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  4. #4
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    Talking hexatodecimal

    #include<iostream.h>
    #include<conio.h>
    #include<stdio.h>
    #include<string.h>
    #include<math.h>
    #include<stdlib.h>
    void main(void)
    {
    clrscr();
    char convert[20]={0};
    int length,count=0,sum=0;
    printf("Enter the number= ");
    gets(convert);
    length=strlen(convert);
    for(int i=length-1;i>=0;i--)
    {
    if(convert[i]>=48&&convert[i]<=57)
    convert[i]-=48;
    else if(convert[i]>=65&&convert[i]<=70)
    convert[i]-=55;
    else if(convert[i]>=97&&convert[i]<=102)
    convert[i]-=87;
    sum+=convert[i]*pow(16,count);
    count++;
    }
    cout<<sum<<endl<<itoa(sum,convert,2);
    getch();
    }

  5. #5
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    How would you convert hex to dec from a saved file*I made it so that when you save, the values are in hex........and I can't turn them back so that they will work*

  6. #6
    Registered User xds4lx's Avatar
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    Why not read them in as strings? Store them then use the previous code to manipulate them? If that doenst work then we need to see some code where you are having problems.
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  7. #7
    I am the worst best coder Quantrizi's Avatar
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    I'm the unregistered person above about the save file problem. When the user saves a file, it has the 0x, and then the hex values. But I can't get it to where when the user loads the file, it's back to it's original numbers.

  8. #8
    Registered User xds4lx's Avatar
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    Well how are you reading the file? Into a char array or as strings? Or you could just read them in as ints, the 0x will be interpreted into a value since you can specify values by hex or oct
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  9. #9
    I am the worst best coder Quantrizi's Avatar
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    they're int's.

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