When I perform the following code, it has a problem:
float number = 999999999;
printf("%lf", number);
The result is 10000000000 instead of 999999999.
Why isn't it 999999999?
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zhaoguangliang
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You will need bignums library of an equivalent of it , and the appropriate types. – Olivier Dulac Dec 28 '16 at 17:11
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It will be 999999999 if you use `decimal`. – tymtam Dec 17 '18 at 22:55
1 Answers
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Typical float can represent exactly about 232 different numbers like 1234.0 and -0.125. 999999999 is not one of them. 10000000000.0f is the closest float alternative.
The approximation occurred during the assignment
float number = 999999999; // Really assigned 10000000000.0f
chux - Reinstate Monica
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Thanks for your answer,but i don't know the mens about "Typical float can represent exactly about 232 different numbers like 1234.0 and -0.125. 999999999 is not one of them. ", can you show me more about it ? – zhaoguangliang Jan 03 '17 at 02:35
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@zhaoguangliang `float` is typically 4 bytes, than is, at most, 4,294,967,296 different floating point numbers. Yet you can code `float number = endless_different_decimal_values_in_text;`. Sometimes code will use a number that is not representable as 1 of those 4 billion. What do you think should happen then? – chux - Reinstate Monica Jan 03 '17 at 02:42