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Converting RGB to Hex

Converting RGB to Hex, i'm new at this i just want to get thru it can someome pls help

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passionfruit	19 Jul, 2008 - 03:50 PM Post #1
New D.I.C Head Joined: 19 Jul, 2008 Posts: 4	create a function that will accept 3 interger parameters (r,b,g) and return a hexadecimal value. The final hexadecimal value will be 3 2 character answers concatenated together...i'm failing this class but i want to know it so baddddd... i just need help cpp stringConvertRGBtohex(int r, int g, int //all ints 255 MAX { string RGB char c; for (int i=2sizeof(int) - 1; i>=0; i--) { c = "0123456789ABCDEF"[((num >> i4) & 0xF)]; rgb += c; } return RBG; } int main() { int n; string hStr; while (cin >> n) { cout << "decimal: " << n << endl; hStr = ConvertRGBtohex n); cout << "RGB: " << hStr << endl << endl; } return hex; } This post has been edited by born2c0de: 20 Jul, 2008 - 09:57 AM
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RodgerB

RE: Converting RGB To Hex
19 Jul, 2008 - 06:43 PM

Post #2

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This worked for me:

cpp


#include <iostream>
#include <string.h>

using namespace std;
string RGBToHex(int rNum, int gNum, int bNum);

int main()
{
	cout << RGBToHex(255, 255, 255).c_str();
	return 0;
}

string RGBToHex(int rNum, int gNum, int bNum)
{
	string result;

	char r[255];	
	sprintf_s(r, "%.2X", rNum);
	result.append(r );

	char g[255];	
	sprintf_s(g, "%.2X", gNum);
	result.append(g );

	char b[255];	
	sprintf_s(b, "%.2X", bNum);
	result.append(b );
	
	return result;
}

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Jayman	RE: Converting RGB To Hex 19 Jul, 2008 - 06:59 PM Post #3
Student of Life Joined: 26 Dec, 2005 Posts: 6,917 Thanked: 42 times Dream Kudos: 500 Expert In: C#, VB.NET, Java My Contributions	Please use tags when posting code.
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baavgai	RE: Converting RGB To Hex 20 Jul, 2008 - 06:05 AM Post #4
Dreaming Coder Joined: 16 Oct, 2007 Posts: 2,018 Thanked: 105 times Dream Kudos: 475 Expert In: C, C++, Java, C#, ASP.NET, PHP, Perl, Python, Oracle, SQL Server, MySql, HTML, JavaScript, Lua My Contributions	Your function says r,g,b but your code says num? Your works, if you actually pass it an integer num and not three integers. So, this works ( after adjusting for some case errors): cpp string ConvertRGBtoHex(int num) { string rgb; char c; for (int i=2sizeof(int) - 1; i>=0; i--) { c = "0123456789ABCDEF"[((num >> i4) & 0xF)]; rgb += c; } return rgb; } However, you probably only want to see three hex bytes, so you might want to fix then length. Here's the same function, altered slightly. cpp string ConvertRGBtoHex(int num) { static string hexDigits = "0123456789ABCDEF"; string rgb; for (int i=(32) - 1; i>=0; i--) { rgb += hexDigits[((num >> i4) & 0xF)]; } return rgb; } Now, if you actually want to pass three values, you can reuse the prior function with this one: CODE string ConvertRGBtoHex(int r, int g, int B) { int rgbNum = ((r & 0xff) << 16) \| ((g & 0xff) << 8) \| (b & 0xff); return ConvertRGBtoHex(rgbNum); } Hope this helps. EDIT: Bloody thing won't turn emo crap off on edit. This post has been edited by baavgai: 20 Jul, 2008 - 06:06 AM
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