Pointer to different data type in C -

i have compiled , run following program in c:

#include <stdio.h> #include <stdint.h> #include <inttypes.h>  int main(int argc, char* argv[]){   uint8_t data[8] = {0, 1, 2, 3, 4, 5, 6, 7};   uint32_t* pointer32 = &data[0];   uint64_t* pointer64 = &data[0];    printf("%" priu64 "\n", *pointer64);   printf("%" priu32 "\n", *(pointer32++));   printf("%" priu32 "\n", *pointer32);    return 0; } 

and received following expected output:

506097522914230528 50462976 117835012 

the output correct , corresponds bitwise interpretation of data unsigned 64-bit integer , unsigned 32-bit integers. tried on 64-bit machine running ubuntu 14.04. compiled stock gcc compiler (4.8.4?). compiler throw "assignment incompatible pointer type" warning (which can safely ignored because incompatible assignment intended).

is reliable way of converting , interpreting data in "data" array, or better recommended manually copy , shift each byte, 1 @ time, temporary variable?

you violating aliasing rules. so, clear answer is: no.

briefly: must not have pointers of different type pointing same object. may result in broken code, compiler assume not happen , might optimize code.

just strong hint: not ignore warnings. given reasons.

the best way serialize/deserialize data array per element final types. avoid problems endianess (byte-ordering) of values , (possible) padding.

i use functions this:

uint32_t readuint32(const uint8_t **buffer) {     ... // increment buffer accordingly } 

this way, pass buffer pointer along line, without having care incrementing in caller. technic iterator.