c - Calculating an integer from its Bytes gives oddly wrong results -

i'm trying read integer data file stored raw in little endian format. once got corresponding bytes calculated integer value adding numbers multiplied weight (aritmetic method below) reason value allways off 1 unit on significant byte.

other methods seem work want know why result wrong when using following code.

#include <stdio.h> #include <stdint.h>  void main(){   //two bytes form 16-bit integer (little endian)   char b[2] = {0xbd, 0x74};    //this gives correct answer (shift + masking)   uint16_t n_correct;   n_correct = (b[0] & 0xff) + ((b[1]<<8) & 0xff00);   //this should give correct answer doesn't (shifting method)   uint16_t n_incorrect;   n_incorrect = b[0] + (b[1]<<8);   //this should give correct answer doesn't (aritmetic)   uint16_t n_arith;   n_arith = b[0] + (b[1]*256);   //this works, on little endian machines. dirty works. (hack)   uint16_t n_hack;   uint8_t* n_ptr = (uint8_t*)&n_hack;   n_ptr[0] = b[0];   n_ptr[1] = b[1];    printf("shifting method: %x == %x%x?\n", n_incorrect, b[1]&0xff, b[0]&0xff);   printf("shift + masking: %x == %x%x?\n", n_correct, b[1]&0xff, b[0]&0xff);   printf("     arithmetic: %x == %x%x?\n", n_arith, b[1]&0xff, b[0]&0xff);   printf("           hack: %x == %x%x?\n", n_hack, b[1]&0xff, b[0]&0xff); } 

the output is:

shifting method: 73bd == 74bd? shift + masking: 74bd == 74bd?      arithmetic: 73bd == 74bd?            hack: 74bd == 74bd? 

as can see, using plain shifting or multiplication gives wrong answer. why?

i've done hundred times. change:

char b[2] = {0xbd, 0x74}; 

to

unsigned char b[2] = {0xbd, 0x74}; 

or, better yet

uint8_t b[2] = {0xbd, 0x74}; 

note char can more 8 bits (i worked on system 32-bit char size)