array to hexadecimal variable

[TheDeveloper]

Please anyone tell me how to convert array to hexadecimal variable

Input:
a = {255, 0, 0, 0 }

I need output as 

a = FF000000 

If input is a = {255, 255, 255, 255 }

Output should be 

a = FFFFFFFF

[Dino]

Use printf() with the %02X formatter in a loop.

[TheDeveloper]

Use printf() with the %02X formatter in a loop.

thanks for your reply

OK, how to get the final value into variable

Say Input is 

a = {255, 0, 0. 0} which is in the format a ={a, r, g, b}

printf("%02x%02x%02x\n", r, g, b);

how to get the final hex values into an variable ?

[Dino]

Use sprintf() instead of printf().

[TheDeveloper]

Use sprintf() instead of printf().

Yes sprintf works if I need to store the formatted text in char. But my requirement is all about to store the hex values in int32. can anyone tell me how to do it ?

char color[10];
	
sprintf(color, "FF%02x%02x%02x", R, G, B);

[nonoob]

I'm sure you don't mean that array a holds the problem as well as the solution.

So something like this:

answer = a[0] << 24 | a[1] << 16 | a[2] << 8 | a[3];

[TheDeveloper]

I'm sure you don't mean that array a holds the problem as well as the solution.

So something like this:

answer = a[0] << 24 | a[1] << 16 | a[2] << 8 | a[3];

so this one works fine ?
cant i do it without sprintf ?

function(R, G, B)
{
char a[10];
u_int32 color;

sprintf(a, "FF%02x%02x%02x", R, G, B);
color = a[0] << 24 | a[1] << 16 | a[2] << 8 | a[3];
}

[nonoob]

OK there are a few confusions here. In your latest example you are passing three integers (I assume). The function should return a composite RGB value?
When you mentioned "Output should be a = FFFFFFFF" you meant you wanted an integer?

Maybe

return a << 24 | R << 16 | G << 8 | B;

Where 'a' is transparency or whatever? You didn't pass this value.

If you want to print out this 32-bit integer as a hex string use

printf("%08X", variable);