1PRINTF(3S)                                                          PRINTF(3S)
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NAME

6       printf, fprintf, sprintf - formatted output conversion
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SYNOPSIS

9       #include <stdio.h>
10
11       printf(format [, arg ] ...  )
12       char *format;
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14       fprintf(stream, format [, arg ] ...  )
15       FILE *stream;
16       char *format;
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18       sprintf(s, format [, arg ] ...  )
19       char *s, format;
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DESCRIPTION

22       Printf  places  output  on  the standard output stream stdout.  Fprintf
23       places output on the named output stream.  Sprintf places  `output'  in
24       the string s, followed by the character `\0'.
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26       Each  of  these  functions  converts, formats, and prints its arguments
27       after the first under control of the first argument.  The  first  argu‐
28       ment  is  a character string which contains two types of objects: plain
29       characters, which are simply copied to the output stream,  and  conver‐
30       sion  specifications,  each  of which causes conversion and printing of
31       the next successive arg printf.
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33       Each conversion specification is introduced by the character  %.   Fol‐
34       lowing the %, there may be
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36       -      an  optional  minus  sign `-' which specifies left adjustment of
37              the converted value in the indicated field;
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39       -      an optional digit string specifying a field width; if  the  con‐
40              verted  value  has fewer characters than the field width it will
41              be blank-padded on the left (or right,  if  the  left-adjustment
42              indicator  has  been  given)  to make up the field width; if the
43              field width begins  with  a  zero,  zero-padding  will  be  done
44              instead of blank-padding;
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46       -      an optional period `.'  which serves to separate the field width
47              from the next digit string;
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49       -      an optional digit string specifying a precision which  specifies
50              the  number  of digits to appear after the decimal point, for e-
51              and f-conversion, or the maximum  number  of  characters  to  be
52              printed from a string;
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54       -      the character l specifying that a following d, o, x, or u corre‐
55              sponds to a long integer arg.  (A  capitalized  conversion  code
56              accomplishes the same thing.)
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58       -      a  character  which  indicates  the  type  of  conversion  to be
59              applied.
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61       A field width or precision may be `*' instead of a  digit  string.   In
62       this case an integer arg supplies the field width or precision.
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64       The conversion characters and their meanings are
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66       dox    The  integer  arg is converted to decimal, octal, or hexadecimal
67              notation respectively.
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69       f      The float or double arg is converted to decimal notation in  the
70              style  `[-]ddd.ddd'  where  the  number of d's after the decimal
71              point is equal to the precision specification for the  argument.
72              If  the  precision is missing, 6 digits are given; if the preci‐
73              sion is explicitly  0,  no  digits  and  no  decimal  point  are
74              printed.
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76       e      The float or double arg is converted in the style `[-]d.ddde±dd'
77              where there is one digit before the decimal point and the number
78              after  is equal to the precision specification for the argument;
79              when the precision is missing, 6 digits are produced.
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81       g      The float or double arg is printed in style d, in style f, or in
82              style e, whichever gives full precision in minimum space.
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84       c      The character arg is printed.  Null characters are ignored.
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86       s      Arg  is  taken to be a string (character pointer) and characters
87              from the string are printed until a null character or until  the
88              number of characters indicated by the precision specification is
89              reached; however if the precision is 0 or missing all characters
90              up to a null are printed.
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92       u      The  unsigned  integer  arg  is converted to decimal and printed
93              (the result will be in the range 0 to 65535).
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95       %      Print a `%'; no argument is converted.
96
97       In no case does a non-existent or small field width cause truncation of
98       a  field; padding takes place only if the specified field width exceeds
99       the actual width.   Characters  generated  by  printf  are  printed  by
100       putc(3).
101
102       Examples
103       To  print  a  date  and time in the form `Sunday, July 3, 10:02', where
104       weekday and month are pointers to null-terminated strings:
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106              printf("%s, %s %d, %02d:%02d", weekday, month, day, hour, min);
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108       To print pi to 5 decimals:
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110              printf("pi = %.5f", 4*atan(1.0));
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SEE ALSO

113       putc(3), scanf(3), ecvt(3)
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BUGS

116       Very wide fields (>128 characters) fail.
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120                                                                    PRINTF(3S)