Reputation: 3833
I am trying to convert a char[] in ASCII to char[] in hexadecimal.
Something like this:
hello --> 68656C6C6F
I want to read by keyboard the string. It has to be 16 characters long.
This is my code now. I don't know how to do that operation. I read about strol but I think it just convert str number to int hex...
#include <stdio.h>
main()
{
int i = 0;
char word[17];
printf("Intro word:");
fgets(word, 16, stdin);
word[16] = '\0';
for(i = 0; i<16; i++){
printf("%c",word[i]);
}
}
I am using fgets because I read is better than fgets but I can change it if necessary.
Related to this, I am trying to convert the string read in a uint8_t array, joining each 2 bytes in one to get the hex number.
I have this function which I am using a lot in arduino so I think it should work in a normal C program without problems.
uint8_t* hex_decode(char *in, size_t len, uint8_t *out)
{
unsigned int i, t, hn, ln;
for (t = 0,i = 0; i < len; i+=2,++t) {
hn = in[i] > '9' ? (in[i]|32) - 'a' + 10 : in[i] - '0';
ln = in[i+1] > '9' ? (in[i+1]|32) - 'a' + 10 : in[i+1] - '0';
out[t] = (hn << 4 ) | ln;
printf("%s",out[t]);
}
return out;
}
But, whenever I call that function in my code, I get a segmentation fault.
Adding this code to the code of the first answer:
uint8_t* out;
hex_decode(key_DM, sizeof(out_key), out);
I tried to pass all necessary parameters and get in out array what I need but it fails...
Upvotes: 16
Views: 145569
Reputation: 1
void atoh(char *ascii_ptr, char *hex_ptr,int len)
{
int i;
for(i = 0; i < (len / 2); i++)
{
*(hex_ptr+i) = (*(ascii_ptr+(2*i)) <= '9') ? ((*(ascii_ptr+(2*i)) - '0') * 16 ) : (((*(ascii_ptr+(2*i)) - 'A') + 10) << 4);
*(hex_ptr+i) |= (*(ascii_ptr+(2*i)+1) <= '9') ? (*(ascii_ptr+(2*i)+1) - '0') : (*(ascii_ptr+(2*i)+1) - 'A' + 10);
}
}
Upvotes: 0
Reputation: 40155
#include <stdio.h>
#include <string.h>
int main(void){
char word[17], outword[33];//17:16+1, 33:16*2+1
int i, len;
printf("Intro word:");
fgets(word, sizeof(word), stdin);
len = strlen(word);
if(word[len-1]=='\n')
word[--len] = '\0';
for(i = 0; i<len; i++){
sprintf(outword+i*2, "%02X", word[i]);
}
printf("%s\n", outword);
return 0;
}
Upvotes: 14
Reputation: 33573
Use the %02X
format parameter:
printf("%02X",word[i]);
More info can be found here: http://www.cplusplus.com/reference/cstdio/printf/
Upvotes: 4