CODEWITHSUNDEEP
cfloating-point
Allen
Allen

Reputation: 47

Floating-point representation error on C

So I want to verify the hexadecimal representation of the number 1.0 in Language C, below are my codes:

int main(int argc, char **argv)
{
    void showBytes(unsigned char * p,int size){
        int i;
        for (i=0;i<size;i++){
            printf("%.2x",p[i]);
        }
    }

    float f;
    f=1.0;
    showBytes((unsigned char *)&f,sizeof(f));
    return 0;
}

When I build and run my program, I get 39300000, which is not the correct representation of 1.0(00003039). Can any one explain to me why I get this incorrect value? Thanks!!!

Upvotes: 0

Views: 305

Answers (1)

David Heffernan
David Heffernan

Reputation: 612964

This is an endianness mis-match. You are displaying the value using one endianness convention, but your expected value uses the other convention.

Endianness is a well-known issue for integer data types, but it is perhaps less well known endianness also affects floating point representation.

Upvotes: 10

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