C convert double to float preserving decimal point precision

Question

i wanted to convert double to float in C  but wanted to preserve the decimal point exactly as possible without any changes     for example  let s say i have     double d   0 1108     double dd   639728 170000     double ddd   345 2345678   now correct me if i am wrong  i know that floating point precision is about 5 numbers after the dot  can i get those five numbers after the dot exactly as the double had it  so that above results as follows      float f   x d      float ff   x dd      float fff   x ddd       printf   f n f n f n   f  ff  fff     it should print     0 1108    639728 17000    345 23456   all digits after the precision limit  which i assume as 5  would be truncated

User · Answer

A float generally has about 7 digits of precision  regardless of the position of the decimal point   So if you want 5 digits of precision after the decimal  you ll need to limit the range of the numbers to less than somewhere around   -100

User · Answer

Floating point numbers are represented in scientific notation as a number of only seven significant digits multiplied by a larger number that represents the place of the decimal place  More information about it on Wikipedia    http   en wikipedia org wiki Floating point

User · Answer

float and double don t store decimal places   They store binary places  float is  assuming IEEE 754  24 significant bits  7 22 decimal digits  and double is 53 significant bits  15 95 significant digits    Converting from double to float will give you the closest possible float  so rounding won t help you   Goining the other way may give you  noise  digits in the decimal representation    include  lt stdio h gt   int main void        double orig   12345 67      float f    float  orig      printf    17g n   f      prints 12345 669921875     return 0      To get a double approximation to the nice decimal value you intended  you can write something like   double round to decimal float f        char buf 42       sprintf buf     7g   f      round to 7 decimal digits     return atof buf

[c] C: convert double to float, preserving decimal point precision

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