Function call within if statement

[deathtospies]

I've got a function f which returns a double. I'm calling that function within an if statement as follows:

if (f(...) > 0.1) cout << 1;
else cout << 0;

I've included print statements within f to display the return value. Sometimes f returns a value under 0.1 but a 1 gets printed anyway. Changing the code to:

double value = f(...);
if (value > 0.1) cout << 1;
else cout << 0;

seems to fix the problem. Unfortunately I haven't been able to consistently replicate the issue so I don't know the conditions under which this happens. Can anybody speculate? Thanks.

[jsmith]

What compiler and version are you using and with what options are you compiling?

There were bugs in some versions of gcc where gcc would generate 32-bit floating point temporaries (floats)
into which it wanted to store a double, which meant loss of precision.

[deathtospies]

I'm using gcc 4.1.2 with options -g -Wno-long-long -c -m32

[jsmith]

Generate the assembler output for the above code and see if it is generating 32-bit or 64-bit floating point instructions.

(You can post it here if you want... I should be able to recognize it if I see it)