PRINTF(3S) COMMAND REFERENCE PRINTF(3S) NAME printf, fprintf, sprintf - formatted output conversion SYNOPSIS #include <stdio.h> int printf(format [ , arg ] ... ) char *format; int fprintf(stream, format [ , arg ] ... ) FILE *stream; char *format; char *sprintf(s, format [ , arg ] ... ) char *s, format; DESCRIPTION Printf places output on the standard output stream stdout. The return value is 0 unless an error occurred, in which case EOF is returned. Fprintf places output on the named output stream. The return value is 0 unless an error occurred, in which case EOF is returned. Sprintf places output in the string s, followed by the character \0. The return value is a pointer to the string s. Each of these functions converts, formats, and prints its arguments after the first, under control of the first argument. The first argument is a character string which contains two types of objects: plain characters, which are simply copied to the output stream, and conversion specifications, each of which causes conversion and printing of the next successive arg printf. Each conversion specification is introduced by the character %. Following the %, there may be, in this order - An optional minus sign (-) which specifies left adjustment of the converted value in the indicated field. - An optional digit string specifying a field width; if the converted value has fewer characters than the field width, it will be blank-padded on the left (or right, if the left-adjustment indicator has been given) to make up the field width; if the field width begins with a zero, zero-padding will be done instead of blank-padding. - An optional dot (.) which serves to separate the field width from the next digit string. Printed 3/13/89 1
PRINTF(3S) COMMAND REFERENCE PRINTF(3S) - An optional digit string specifying a precision which specifies the number of digits to appear after the decimal point, for e- and f-conversion, or the maximum number of characters to be printed from a string - An optional # character specifying that the value should be converted to an alternate form. For c, d, s, and u conversions, this option has no effect. For o conversions, the precision of the number is increased to force the first character of the output string to a zero. For x(X) conversion, a nonzero result has the string 0x(0X) prepended to it. For e, E, f, g, and G conversions, the result will always contain a decimal point, even if no digits follow the point (normally, a decimal point only appears in the results of those conversions if a digit follows the decimal point). For g and G conversions, trailing zeros are not removed from the result as they would otherwise be. - The character l specifying that a following d, o, x, or u corresponds to a long integer arg. - A character which indicates the type of conversion to be applied. A field width or precision may be * instead of a digit string. In this case an integer arg supplies the field width or precision. The conversion characters and their meanings are: dox The integer arg is converted to decimal, octal, or hexadecimal notation respectively. f The float or double arg is converted to decimal notation in the style [-]ddd.ddd where the number of d's after the decimal point is equal to the precision specification for the argument. If the precision is missing, six digits are given; if the precision is explicitly 0, no digits and no decimal point are printed. e The float or double arg is converted in the style [-]d.ddde+dd where there is one digit before the decimal point and the number after is equal to the precision specification for the argument; when the precision is missing, six digits are produced. g The float or double arg is printed in style d, in style f, or in style e, whichever gives full precision in minimum space. Printed 3/13/89 2
PRINTF(3S) COMMAND REFERENCE PRINTF(3S) c The character arg is printed. s Arg is taken to be a string (character pointer) and characters from the string are printed until a null character or until the number of characters indicated by the precision specification is reached; however if the precision is 0 or missing, all characters up to a null are printed. u The unsigned integer arg is converted to decimal and printed (the result will be in the range 0 through MAXUINT, where MAXUINT equals 4294967295). % Print a %; no argument is converted. In no case does a nonexistent or small field width cause truncation of a field; padding takes place only if the specified field width exceeds the actual width. Characters generated by printf are printed by putc(3s). EXAMPLES To print a date and time in the form Sunday, July 3, 10:02, where weekday and month are pointers to null-terminated strings: printf("%s, %s %d, %02d:%02d", weekday, month, day, hour, min); To print pi to five decimals: printf("pi = %.5f", 4*atan(1.0)); CAVEATS It is up the the programmer to ensure that the parameters passed to printf match the format string. Programming errors which cause a type mismatch may induce fatal runtime errors. Also, very wide specifier fields (>128 characters) fail. SEE ALSO putc(3s), scanf(3s), and ecvt(3c). Printed 3/13/89 3
%%index%% na:312,106; sy:418,1908; de:2326,2149;4859,2786;8029,968; ex:8997,440; ca:9437,343; se:9780,169; %%index%%000000000130