What is the difference between g and f in C

Question

I was going through The C programming Language by K amp R  Here in a statement to print a double variable it is written   printf   t g n   sum    atof line      where sum is declared as double  Can anybody please help me out when to use  g in case of double or in case of float and whats the difference between  g and  f

User · Answer

f and  g does the same thing  Only difference is that  g is the shorter form of  f  That is the precision after decimal point is larger in  f compared to  g

User · Answer

See any reference manual  such as the man page      f F      The double argument is rounded and converted to decimal notation in the style  - ddd ddd  where the number of digits after the decimal-point character is equal to the precision specification  If the precision is missing  it is taken as 6  if the precision is explicitly zero  no decimal-point character appears  If a decimal point appears  at least one digit appears before it     The SUSv2 does not know about F and says that character string representations for infinity and NaN may be made available  The C99 standard specifies   - inf  or   - infinity  for infinity  and a string starting with  nan  for NaN  in the case of f conversion  and   - INF  or   - INFINITY  or  NAN   in the case of F conversion        g G      The double argument is converted in style f or e  or F or E for G conversions   The precision specifies the number of significant digits  If the precision is missing  6 digits are given  if the precision is zero  it is treated as 1  Style e is used if the exponent from its conversion is less than -4 or greater than or equal to the precision  Trailing zeros are removed from the fractional part of the result  a decimal point appears only if it is followed by at least one digit

User · Answer

They are both examples of floating point input output     g and  G are simplifiers of the scientific notation floats  e and  E      g will take a number that could be represented as  f  a simple float or double  or  e  scientific notation  and return it as the shorter of the two   The output of your print statement will depend on the value of sum

User · Answer

E   exponent expression  simply means power 10  n  or 10   n   F   fraction expression  default 6 digits precision   G   gerneral expression  somehow smart to show the number in a concise way  but really    See the below example  The code void main int argc  char  argv                  double a   4 5          printf  quot   gt  gt  gt  gt  below is the example for printf 4 5 n quot            printf  quot   e  e n quot  a           printf  quot   f  f n quot  a           printf  quot   g  g n quot  a           printf  quot   E  E n quot  a           printf  quot   F  F n quot  a           printf  quot   G  G n quot  a                      double b   1 79e308          printf  quot   gt  gt  gt  gt  below is the exbmple for printf 1 79 10 308 n quot            printf  quot   e  e n quot  b           printf  quot   f  f n quot  b           printf  quot   g  g n quot  b           printf  quot   E  E n quot  b           printf  quot   F  F n quot  b           printf  quot   G  G n quot  b            double d   2 25074e-308          printf  quot   gt  gt  gt  gt  below is the example for printf 2 25074 10 -308 n quot            printf  quot   e  e n quot  d           printf  quot   f  f n quot  d           printf  quot   g  g n quot  d           printf  quot   E  E n quot  d           printf  quot   F  F n quot  d           printf  quot   G  G n quot  d        The output   gt  gt  gt  gt  below is the example for printf 4 5  e 4 500000e 00  f 4 500000  g 4 5  E 4 500000E 00  F 4 500000  G 4 5   gt  gt  gt  gt  below is the exbmple for printf 1 79 10 308  e 1 790000e 308  f 178999999999999996376899522972626047077637637819240219954027593177370961667659291027329061638406108931437333529420935752785895444161234074984843178962619172326295244262722141766382622299223626438470088150218987997954747866198184686628013966119769261150988554952970462018533787926725176560021258785656871583744 000000  g 1 79e 308  E 1 790000E 308  F 178999999999999996376899522972626047077637637819240219954027593177370961667659291027329061638406108931437333529420935752785895444161234074984843178962619172326295244262722141766382622299223626438470088150218987997954747866198184686628013966119769261150988554952970462018533787926725176560021258785656871583744 000000  G 1 79E 308   gt  gt  gt  gt  below is the example for printf 2 25074 10 -308  e 2 250740e-308  f 0 000000  g 2 25074e-308  E 2 250740E-308  F 0 000000  G 2 25074E-308

User · Answer

As Unwind points out f and g provide different default outputs     Roughly speaking if you care more about the details of what comes after the decimal point I would do with f and if you want to scale for large numbers go with g   From some dusty memories f is very nice with small values if your printing tables of numbers as everything stays lined up but something like g is needed if you stand a change of your numbers getting large and your layout matters   e is more useful when your numbers tend to be very small or very large but never near ten     An alternative is to specify the output format so that you get the same number of characters representing your number every time     Sorry for the woolly answer but it is a subjective out put thing that only gets hard answers if the number of characters generated is important or the precision of the represented value

[c] What is the difference between %g and %f in C?

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