C-将十六进制值转换为int并存储在char数组中

Question

I have the following code,

int main(){
  const char *hexstring = "f";
  int number = (int)strtoul(hexstring, NULL, 16);

  printf("%d", number); //Prints 15
  char s[5];
  s[0] = number; 
  printf("%d", s[0]); //prints 15
}

I ran it for "1F" and it returns 31 as expected.

if, hexString value is FF or any other value which results in 3 digit number, s[0] returns a negative value.

What am i doing wrong? How can i make s[0] hold 255 in case hexString is "FF".

Answer 1

char can be signed or unsigned. It looks like char is signed on your platform. In your case you want to use unsigned char .

Change:

char s[5];

to:

unsigned char s[5];