Cast byte array to float
c, c++, casting
Solution
Indeed, this is an endianness issue:
#include <stdio.h>
#include <stdint.h>
int main()
{
union {
uint8_t bytes[4];
float f;
} fun1 = { .bytes = { 0x41, 0xd7, 0xd1, 0xe1} }, fun2 = { .bytes = { 0xe1, 0xd1, 0xd7, 0x41} };
printf("%f\n%f\n", fun1.f, fun2.f);
return 0;
}
This prints:
-483860023749617123328.000000
26.977480
Problem
I have a program that needs to take in 4 bytes and convert them to an IEEE-754 float. The bytes are transferred out of order, but I can put them back in order just fine. My problem is casting them to a float. The relevant parts of code: ``` //Union to store bytes and float on top of each other typedef union { unsigned char b[4]; float f; } bfloat; //Create instance of the union bfloat Temperature; //Add float data using transmitted bytes MMI.Temperature.b[2] = 0xD1;//MMIResponseMsg[7]; MMI.Temperature.b[3] = 0xE1;//MMIResponseMsg[8]; MMI.Temperature.b[0] = 0x41;//MMIResponseMsg[9]; MMI.Temperature.b[1] = 0xD7;//MMIResponseMsg[10]; //Attempting to read the float value lWhole=(long) ((float)MMI.Temperature.f); //DEBUGGING stevenFloat = (float)MMI.Temperature.f; ``` `lWhole` is a long and `stevenFloat` is a float. When debugging I can see that the values I assign to the byte array are being stored correctly, however the values of `stevenFloat` and `lWhole` are incorrect. They seem to hover close to 0, or close to the max float/long values. A long and float are both 32 bits with my compiler. Does anyone know why this isn't working? It looked correct to me when I received the code to work on and it appears to be a common solution online, I am just stumped.