Question

Anyway have any idea how to do this?

Let’s say i have

char x[] = "ABCD";

and i want to put it into an int, so i’ll have

int y = 'ABCD';

I can only put individual chars, such as int y = x[0]; The purpose is to find the decimal representation, but i want the decimal representation of “ABCD” not just “A”.

Finally i would use sprintf(dest, "%.2u", value); to get the decimal representation of the char.

EDIT:

I dont understand why, but for “ABCD” this code works

//unrolled bit ops
const char* x = "ABCD";
uint32_t y = 0;
y |= (uint32_t(x[0]) << 24); //MSB
y |= (uint32_t(x[1]) << 16);
y |= (uint32_t(x[2]) <<  8);
y |= (uint32_t(x[3]) /*<< 0*/);

however, per instance if i use “(¸þ¶” i dont get the same result.

EDIT2 **:

I’ve tried your last edit Sam, but it still doesnt work. The value i’m getting is “4294967294” as opposed to “683212470” the correct value.
I also did this

int h1 = '(';
int h2 = '¸';
int h3 = 'þ';
int h4 = '¶';

Output:

40
-72
-2
-74

I googled for the complete ascii table, and i found out that for “þ” the value is “254”. I suppose it has something to do with this… i also tried with usigned but no good results.

edit3: If i replace const char *x = "(¸þ¶" with int x[] = {40, 184, 254, 182}; (decimal representation of each character, it works. I can understand where things go wrong, but i have no idea how to fix it.

Answer 1

You need to assure int alignment for that char array for a proper cast or do a memcpy into that int.
Also take care of the integer’s endianness! Furthermore, usage of C99 integer types such as uint32_t, will also help to make your code portable.

See this question for how to convert the bits:
strict aliasing and alignment

EDIT:

What R. Martinho Fernandes means, might be this (not tested):

//unrolled bit ops
const char* x = "ABCD";
uint32_t y = 0;
y |= (uint32_t(uint8_t(x[0])) << 24); //MSB
y |= (uint32_t(uint8_t(x[1])) << 16);
y |= (uint32_t(uint8_t(x[2])) <<  8);
y |= (uint32_t(uint8_t(x[3])) /*<< 0*/);

Above example avoids specific code for any endianness

EDIT 2:

For dynamic char arrays (assuming leading zero chars if less than 4 have to be converted):

const char* x = "ABC";
size_t nChars = 3;

assert(0 < nChars && nChars <= sizeof(uint32_t));

uint32_t y = 0;

int shift = (nChars*8)-8;
for(size_t i = 0;i < nChars;++i)
{
    y |= (uint32_t(uint8_t(x[i])) << shift);
    shift -= 8;
}