Convert ascii char to hexadecimal char in C

Question

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  lt stdio h gt  main         int i   0      char word 17        printf  Intro word          fgets word  16  stdin       word 16      0       for i   0  i lt 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  lt  len  i  2   t                 hn   in i   gt   9     in i  32  -  a    10   in i  -  0               ln   in i 1   gt   9     in i 1  32  -  a    10   in i 1  -  0                out t     hn  lt  lt  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

User · Answer

replace this  printf   c  word i      by  printf   02X  word i

User · Answer

include  lt stdio h gt   include  lt string h gt   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 lt len  i             sprintf outword i 2    02X   word i              printf   s n   outword       return 0

User · Answer

Use the  02X format parameter   printf   02X  word i      More info can be found here  http   www cplusplus com reference cstdio printf

User · Answer

void atoh char  ascii ptr  char  hex ptr int len        int i       for i   0  i  lt   len   2   i                     hex ptr i         ascii ptr  2 i    lt    9         ascii ptr  2 i   -  0     16           ascii ptr  2 i   -  A     10   lt  lt  4             hex ptr i         ascii ptr  2 i  1   lt    9        ascii ptr  2 i  1  -  0         ascii ptr  2 i  1  -  A    10

[c] Convert ascii char[] to hexadecimal char[] in C

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