First lets say we have declared a char value as here:

char someChar = '5';

Okay if you simply want to change the type from char to int then you would do something like this

atoi(&someChar);

However note that this simply changes the type from char to int. It will not convert a letter value to the ASCII number that represents it. So like the letter a would really be 97, but I do not think if you used the code above it would give you 97. It would probably make the type an int, but the value 0.

Anyway if you want to actually convert the letter to the number that represents it in ASCII terms you would simply do:

int(someChar);

Oops, I was wrong, looks like atoi does work. I got it wrong the first time because I forgot the & address operator.

Do you know how to concat a single char to the end of a char array? I tried strcat but seems like it's not working. I get the following error message:

warning: passing arg 2 of `strcat' makes pointer from integer without a cast

Here is how I declared the character array and other variables:

unsigned char a[256], b, c

I want to concat b and c into a. I attempted to do this with the following C code:

strcat(a, b);
strcat(a, c);

When I do that, the above error is thrown.

I just found out there is a problem with using atoi. I used:

n = atoi(&c);

where c is a variable declared as:

char c[256];

but then when I printf the n, it turns out it is 0. It's of ZERO value! How could that be? Actually I want to get the value of that char, like a char 0x80. I want to get the value int 8 in decimal. You have any idea?

Yup re-read what I said above. You will see I already explained that about the character turning to 0. Goto the top and re-read everything 😁

o...yes everything's alright now
cool thanz !! 😁

Can you tell me how can I use the int(someChar); code above using ANSI C?

I want to convert, for example a character A to its ASCII decimal integer number with the value of 65.

Finally, i've found the answer to what i was looking for.

char dest = 'a';
int c = (int)dest;

and c has the ASCII value of a which is 97 dec or 61 hex, but this will work only for one character. Does anyone knows how to do this for a string? For example for the string abc we should have an integer with the value 616263 hex?

You mean the value 0x414243? Or the value 0x434241?

For the string abc, the values are stored as {'a','b','c',0} in the array. So you could use:

char* x = "abc";
int k;

k = *(int*)x; /* assigns 0x434241 on little-endian machines with 32-bit ints */

That's a pretty bad way to do it, though, since it's extremely non-portable. (If you use it on a big-endian machine, you'll get 0x41424300.) And I don't even think it's the value you want.

To get the value 0x414243 from a string like abc, you could write a little function that looks at each character:

unsigned int weird_int_value(char* s) {
  int ret = 0;
  ret = s[0] * 65536;
  ret = ret + s[1] * 256;
  ret = ret + s[2];
  return ret;
}

The problem with this is, it only works on three-character strings. Do you want the same function to take ab and return 0x4142?

The problem with this in general is that it could only possibly work up to 4-byte strings (assuming sizeof(int) is 4 bytes, which it usually is), so it seems like a kind of silly thing to want to do.

So with all of that said, what exactly are you trying to do?

I think what stzo wants is to take a character array and convert each of the character in the array into it's integer equivalent and concat those values together.

An example of what I think he wants to do:

main()
{
  char[2] input='abc';

  for(int trav=0;trav < 2;trav++)
    cout << (int)dest[trav];

}

Something to that affect.

The thing that I want to do is to convert a char = 'abc' to int = '0x616263', which is something like sevster mentioned above.

I am receiving from the serial port some bytes that are stored into a char, and then put the equivalent value of the char's characters concatenated together in an int so as to use this to a CGI file. However, I manage something with the a = (int)char[0] but it works only for the the char[0].