PHP floating point calculation comparison and inaccurate solutions to rounding, inaccurate rounding_PHP tutorial

Solution to inaccurate floating-point calculation comparison and rounding in PHP. Inaccurate rounding

An interesting phenomenon in PHP that should be seen in many programming languages. This is due to the problem of the computer’s own recognition of floating point numbers....

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1. $f = 0.58;
2. var_dump(intval($f * 100 *100)); //result 5799
3. var_dump((float)($f * 100 *100)); //result 5800
4. echo (int)((0.1 0.7)*10); //Result 7
5. echo (float)((0.1 0.7)*10); //Result 8

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2. $a = 0.1;
3. $b = 0.7;
4. var_dump(($a $b) == 0.8);
5. //The printed value is actually boolean false

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2. $a = 0.1;
3. $b = 0.7;
4. var_dump(bcadd($a,$b,2) == 0.8);// bool true

When calculating floating point numbers, remember not to convert floating point numbers into integers, otherwise unpredictable errors will occur.

So never trust that a floating point number result is accurate to the last digit, and never compare two floating point numbers to see if they are equal.

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