c - Pointer Error: Makes pointer from integer without a cast -

i'm brand new c, , i'm trying write function replaces specific byte in unsigned int. pointers still have me little fuzzy--would care explain me error conceptually these pointers in replace_byte()? in advance :)

#include <stdio.h>   typedef unsigned char *byte_pointer;   void show_bytes(byte_pointer start, int length) {     int i;     (i=0; < length; i++) {         printf(" %.2x", start[i]);     }     printf("\n"); }  unsigned replace_byte(unsigned x, int i, unsigned char b) {     int length = sizeof(unsigned);     printf("x: ");     show_bytes(x, length);     printf("replace byte position left: %u\n", i);     printf("replace with: %u\n", b);     printf("combined: ");     int locationfromright = (length - - 1);     x[locationfromright] =  b;     show_bytes( (byte_pointer)&x, length);  }  int main(void) {      unsigned = 0x12345678;     int loc = 2;     unsigned char replacewith = 0xab;     replace_byte(a, loc, replacewith);      return 0; } 

your function definition

void show_bytes(byte_pointer start, int length) 

takes pointer first argument

typedef unsigned char *byte_pointer; 

however in function replace_byte()

unsigned replace_byte(unsigned x, int i, unsigned char b)  

you pass x declared type unsigned show_bytes()

show_bytes(x, length);