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Topic: Hexadecimal Conversion (Read 834 times) |
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kens
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Posts: 59
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Hexadecimal Conversion
« on: Jul 24th, 2007, 2:32pm » |
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Write a function to convert a hexadecimal number into binary.
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I_am_searching
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Re: Hexadecimal Conversion
« Reply #1 on: Jul 24th, 2007, 2:41pm » |
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Does that mean we need to print the binary equivalent of the number?... If yes.. then how is the hexadecimal number inputed. Is it inputed as a string?
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kens
Junior Member
Posts: 59
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Re: Hexadecimal Conversion
« Reply #2 on: Jul 24th, 2007, 2:58pm » |
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The haxadecimal number can be declared as a variable in the main and initialized. Or,the main may take string input and convert to hexadecimal and pass it to a function that prints the output in binary.
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I_am_searching
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Re: Hexadecimal Conversion
« Reply #3 on: Jul 24th, 2007, 3:12pm » |
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Kool..
I would then follow a very simple approach of pre compute and use the values.
I have a string array of size 16.
arr[0]="0000"
arr[1]="0001"
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arr[14]="1110"
arr[15]="1111"
Though this might not be that space efficient but it saves alot of time in actually computing these values. This kind of approach helps alot where time complexity is give importance over space.
Algo
start reading the input hexa decimal string.
for(i=0;i<strlen(input);i++)
{
ch=input[i];
if( ch >= 48 && ch <=57)
index=ch-'0';
else if(ch >= 65 && ch <= 70)
index=10+ch-'A';
else if(ch >=97 && ch <=102)
index=10+ch-'a';
else
{
printf("Invalid Input")
return;
}
strcat(output,arr[index]);
}
return output;
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towr
wu::riddles Moderator
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Re: Hexadecimal Conversion
« Reply #4 on: Jul 24th, 2007, 3:14pm » |
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If we consider string input and output
table[16] = { "0000", "0001" ... etc}
while(input)
{
s= *intput++;
if (s >='a')
printf("%s", table[10+s-'a']);
else
printf("%s", table[s-'0']);
}
[edit]Seems like I was beaten to it (and I ignored potential invalid input)[/edit]
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| « Last Edit: Jul 24th, 2007, 3:15pm by towr » |
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Wikipedia, Google, Mathworld, Integer sequence DB
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Margit
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Re: Hexadecimal Conversion
« Reply #5 on: Jul 26th, 2007, 12:53am » |
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Hmm.
if( ch >= 48 && ch <=57)
index=ch-'0';
else if(ch >= 65 && ch <= 70)
index=10+ch-'A';
else if(ch >=97 && ch <=102)
Doesn't work on EBCDIC machines eg. IBM "big iron" boxen.
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| « Last Edit: Jul 26th, 2007, 12:59am by Margit » |
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I_am_searching
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Re: Hexadecimal Conversion
« Reply #6 on: Jul 26th, 2007, 1:02am » |
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We can change this to...
if( ch >= '0' && ch <='9')
index=ch-'0';
else if(ch >= 'A' && ch <= 'F')
index=10+ch-'A';
else if(ch >='a' && ch <= 'f')
index=10+ch-'a';
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Grimbal
wu::riddles Moderator
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Re: Hexadecimal Conversion
« Reply #7 on: Jul 26th, 2007, 2:39am » |
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In Java, assuming the input is a string:
Integer.toString(Integer.parseInt(hexNumber, 16), 2)
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Sameer
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Re: Hexadecimal Conversion
« Reply #8 on: Jul 26th, 2007, 9:13am » |
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Create an associative array and use the hex number as the index to get respective binary value..
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| « Last Edit: Jul 26th, 2007, 9:13am by Sameer » |
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"Obvious" is the most dangerous word in mathematics.
--Bell, Eric Temple
Proof is an idol before which the mathematician tortures himself.
Sir Arthur Eddington, quoted in Bridges to Infinity
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mad
Junior Member
Posts: 118
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integer using putchar
« Reply #9 on: Jul 31st, 2007, 12:50pm » |
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Print an integer using only putchar. Try doing it without using extra storage.
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Grimbal
wu::riddles Moderator
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Re: integer using putchar
« Reply #10 on: Aug 2nd, 2007, 7:55am » |
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on Jul 31st, 2007, 12:50pm, mad wrote:| Print an integer using only putchar. Try doing it without using extra storage. |
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switch( n ){
case 0; putchar('0'); break;
case -1: putchar('-'); // fallthrough
case 1: putchar('1'); break;
case -2: putchar('-'); // fallthrough
case 2: putchar('2'); break;
...
}
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baba
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Re: Hexadecimal Conversion
« Reply #11 on: Aug 21st, 2007, 4:48am » |
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Hey Grimbal what abt something like
void PrintWithoutExtraStorage(int n)
{
if (n>10)
PrintWithoutExtraStorage(n/10);
putchar(n%10+'0');
}
Assuming we don't count the stack used for recursion as extra storage. 
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Grimbal
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Re: Hexadecimal Conversion
« Reply #12 on: Aug 21st, 2007, 5:01am » |
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on Aug 21st, 2007, 4:48am, baba wrote:| Assuming we don't count the stack used for recursion as extra storage. |
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That's the problem.
And what happens when n=10?
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| « Last Edit: Aug 21st, 2007, 5:03am by Grimbal » |
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baba
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Re: Hexadecimal Conversion
« Reply #13 on: Aug 21st, 2007, 6:13am » |
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on Aug 21st, 2007, 5:01am, Grimbal wrote:
And what happens when n=10? |
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Nice catch...just change the comparison to (n>=10)
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