c++ - floating point representation in memory is just not clear for me -

my task get fraction of float store in int. seemed easy. did test:

float f = 3.1415f; printf("int pres. of float: %d\n"        "int:                %d", *((int *)&f), 31415);

output:

int pres. of float: 1078529622

int: 31415

i changed them base 2 see 31415 present.

0100 0000 0100 1001 0000 1110 0101 0110 - 3.1415                     0111 1010 1011 0111 - 31415

i don't know do. how fraction simple integer?

if take 2.5, instead of 3.1415, because it's easy understand...

so assumption 2.5 , 25 should have same binary format. not case. 25 = 0x19 = 11001. 2.5 = 10.1. not @ same thing.

if feel doing same sort of math 3.1415, goes this:

3      = 11 (i can that) 1/8    = 0.001   0.1415 - 0.125 = 0.0165 1/64   = 0.000001 0.0165 - 0.015625 = 0.000875 1/2048 = 0.00000000001

and still have fractions of 0.1415 left deal @ point, rough result 11.00100100001.

now, if compare binary output (starting @ mantissa part), , inserting decimal point, , take account floating point numbers "ignore first one":

  11.00100100001    1.00100100001110

seems scribbles above aren't off... ;)

Shashtri