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Annotation of 43BSDReno/lib/libc/stdio/scanf.3, revision 1.1

1.1     ! root        1: .\"    @(#)scanf.3     6.2 (Berkeley) 4/1/89
        !             2: .\"
        !             3: .TH SCANF 3  "April 1, 1989"
        !             4: .AT 3
        !             5: .SH NAME
        !             6: scanf, fscanf, sscanf \- formatted input conversion
        !             7: .SH SYNOPSIS
        !             8: .B #include <stdio.h>
        !             9: .PP
        !            10: .B scanf(format
        !            11: [ , pointer ] . . .
        !            12: .B )
        !            13: .br
        !            14: .B char *format;
        !            15: .PP
        !            16: .B fscanf(stream, format
        !            17: [ , pointer ] . . .
        !            18: .B )
        !            19: .br
        !            20: .SM
        !            21: .B FILE
        !            22: .B *stream;
        !            23: .br
        !            24: .B char *format;
        !            25: .PP
        !            26: .B sscanf(s, format
        !            27: [ , pointer ] . . .
        !            28: .B )
        !            29: .br
        !            30: .B char *s, *format;
        !            31: .SH DESCRIPTION
        !            32: .I Scanf
        !            33: reads from the standard input stream
        !            34: .BR stdin .
        !            35: .I Fscanf
        !            36: reads from the named input
        !            37: .IR stream .
        !            38: .I Sscanf
        !            39: reads from the character string
        !            40: .IR s .
        !            41: Each function reads characters, interprets
        !            42: them according to a format, and stores the results in its arguments.
        !            43: Each expects as arguments
        !            44: a control string
        !            45: .IR format ,
        !            46: described below,
        !            47: and a set of
        !            48: .I pointer
        !            49: arguments
        !            50: indicating where the converted input should be stored.
        !            51: .PP
        !            52: The
        !            53: control string
        !            54: usually contains
        !            55: conversion specifications, which are used to direct interpretation
        !            56: of input sequences.
        !            57: The control string may contain:
        !            58: .TP 4
        !            59: 1.
        !            60: Blanks, tabs or newlines,
        !            61: which match optional white space in the input.
        !            62: .TP 4
        !            63: 2.
        !            64: An ordinary character (not %) which must match
        !            65: the next character of the input stream.
        !            66: .TP 4
        !            67: 3.
        !            68: Conversion specifications, consisting of the
        !            69: character
        !            70: .BR % ,
        !            71: an optional assignment suppressing character
        !            72: .BR * ,
        !            73: an optional numerical maximum field width, and a conversion
        !            74: character.
        !            75: .PP
        !            76: A conversion specification directs the conversion of the
        !            77: next input field; the result
        !            78: is placed in the variable pointed to by the corresponding argument,
        !            79: unless assignment suppression was
        !            80: indicated by
        !            81: .BR * .
        !            82: An input field is defined as a string of non-space characters;
        !            83: it extends to the next inappropriate character or until the field
        !            84: width, if specified, is exhausted.
        !            85: .PP
        !            86: The conversion character indicates the interpretation of the
        !            87: input field; the corresponding pointer argument must
        !            88: usually be of a restricted type.
        !            89: The following conversion characters are legal:
        !            90: .TP 4
        !            91: .B  %
        !            92: a single `%' is expected
        !            93: in the input at this point;
        !            94: no assignment is done.
        !            95: .TP 4
        !            96: .B  d
        !            97: a decimal integer is expected;
        !            98: the corresponding argument should be an integer pointer.
        !            99: .TP 4
        !           100: .B  o
        !           101: an octal integer is expected;
        !           102: the corresponding argument should be a integer pointer.
        !           103: .TP 4
        !           104: .B  x
        !           105: a hexadecimal integer is expected;
        !           106: the corresponding argument should be an integer pointer.
        !           107: .ti -0.2i
        !           108: .TP 4
        !           109: .B  s
        !           110: a character string is expected;
        !           111: the corresponding argument should be a character pointer
        !           112: pointing to an array of characters large enough to accept the
        !           113: string and a terminating `\e0', which will be added.
        !           114: The input field is terminated by a space character
        !           115: or a newline.
        !           116: .TP 4
        !           117: .B  c
        !           118: a character is expected; the
        !           119: corresponding argument should be a character pointer.
        !           120: The normal skip over space characters is suppressed
        !           121: in this case;
        !           122: to read the next non-space character, try
        !           123: `%1s'.
        !           124: If a field width is given, the corresponding argument
        !           125: should refer to a character array, and the
        !           126: indicated number of characters is read.
        !           127: .TP 4
        !           128: \z\fBe\v'1'f\v'-1'\fR
        !           129: a
        !           130: floating point number is expected;
        !           131: the next field is converted accordingly and stored through the
        !           132: corresponding argument, which should be a pointer to a
        !           133: .IR float .
        !           134: The input format for
        !           135: floating point numbers is
        !           136: an optionally signed
        !           137: string of digits
        !           138: possibly containing a decimal point, followed by an optional
        !           139: exponent field consisting of an E or e followed by an optionally signed integer.
        !           140: .TP 4
        !           141: .B  [
        !           142: indicates a string not to be delimited by space characters.
        !           143: The left bracket is followed by a set of characters and a right
        !           144: bracket; the characters between the brackets define a set
        !           145: of characters making up the string.
        !           146: If the first character
        !           147: is not circumflex (\|^\|), the input field
        !           148: is all characters until the first character not in the set between
        !           149: the brackets; if the first character
        !           150: after the left bracket is ^, the input field is all characters
        !           151: until the first character which is in the remaining set of characters
        !           152: between the brackets.
        !           153: The corresponding argument must point to a character array.
        !           154: .PP
        !           155: The conversion characters
        !           156: .BR d ,
        !           157: .B o
        !           158: and
        !           159: .B x
        !           160: may be capitalized or preceded by
        !           161: .B l
        !           162: to indicate that a pointer to
        !           163: .B long
        !           164: rather than to
        !           165: .B int
        !           166: is in the argument list.
        !           167: Similarly, the conversion characters
        !           168: .B e
        !           169: or
        !           170: .B f
        !           171: may be capitalized or
        !           172: preceded by
        !           173: .B l
        !           174: to indicate a pointer to 
        !           175: .B double
        !           176: rather than to 
        !           177: .BR float .
        !           178: The conversion characters
        !           179: .BR d ,
        !           180: .B o
        !           181: and
        !           182: .B x
        !           183: may be preceded by
        !           184: .B h
        !           185: to indicate a pointer to
        !           186: .B short
        !           187: rather than to
        !           188: .BR int .
        !           189: .PP
        !           190: The
        !           191: .I scanf
        !           192: functions return the number of successfully matched and assigned input
        !           193: items.
        !           194: This can be used to decide how many input items were found.
        !           195: The constant
        !           196: .SM
        !           197: .B EOF
        !           198: is returned upon end of input; note that this is different
        !           199: from 0, which means that no conversion was done;
        !           200: if conversion was intended, it was frustrated by an
        !           201: inappropriate character in the input.
        !           202: .PP
        !           203: For example, the call
        !           204: .IP "" 10
        !           205: int i; float x; char name[50];
        !           206: .br
        !           207: scanf("%d%f%s", &i, &x, name);
        !           208: .PP
        !           209: with the input line
        !           210: .IP
        !           211: 25   54.32E\(mi1  thompson
        !           212: .PP
        !           213: will assign to
        !           214: .I i
        !           215: the value
        !           216: 25,
        !           217: .I x
        !           218: the value 5.432, and
        !           219: .I name
        !           220: will contain
        !           221: .IR `thompson\e0' .
        !           222: Or,
        !           223: .IP
        !           224: int i; float x; char name[50];
        !           225: .br
        !           226: scanf("%2d%f%*d%[1234567890]", &i, &x, name);
        !           227: .PP
        !           228: with input
        !           229: .IP
        !           230: 56789 0123 56a72
        !           231: .PP
        !           232: will assign 56 to
        !           233: .IR i ,
        !           234: 789.0 to
        !           235: .IR x ,
        !           236: skip `0123',
        !           237: and place the string `56\e0' in
        !           238: .IR name .
        !           239: The next call to
        !           240: .I getchar
        !           241: will return `a'.
        !           242: .SH "SEE ALSO"
        !           243: atof(3),
        !           244: getc(3),
        !           245: printf(3)
        !           246: .SH DIAGNOSTICS
        !           247: The 
        !           248: .I scanf
        !           249: functions return
        !           250: .SM
        !           251: .B EOF
        !           252: on end of input,
        !           253: and a short count for missing or illegal data items.
        !           254: .SH BUGS
        !           255: The success of literal matches and suppressed
        !           256: assignments is not directly
        !           257: determinable.

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