c - Send data from Host App to Chrome Extension -

after hours of work, i'm able run extension , host app when activate extension, everytime try receive data, undefined.

this code:

int main(int argc, char* argv[]) {     char message[] = "{\"t\": \"t\"}";      unsigned int len = strlen(message);     _setmode(_fileno(stdout), _o_binary);      printf("%c%c%c%c", (char) 10, (char) 0, (char) 0, (char) 0);      printf("%s", message);      return 0; } 

what doing wrong?

%c takes int argument (intrpreted unsigned char), not char. can/will result in wrong data being printed. strlen returns size_t. should read man-pages of functions use.

important: when passing binary values (not characters), should either use uint8_t or - @ least unsigned char. remember char can signed or unsigned, depending on implementation. might lead surprises on arithmetic operations.

note:

printf("%c%c%c%c", (char) 10, (char) 0, (char) 0, (char) 0); printf("%s", message); 

can combined (casts removed):

printf("%c%c%c%c%s", 10, 0, 0, 0, message); 

if there no library support, should think writing functions serialize basic types like:

static void print_u32(uint32_t value) {     ( size_t n = 0 ; n < 4 ; n-- ) {         putc((unsigned char)value);  // still passing int !         value >>= 8;     } }  ... print_string( ...  print_u32(strlen(message)); print_string(message); 

note _setmode not standard library function. after googling, seems bsd extension supported windows (just in case want extension portable).