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Annotation of cci/usr/src/man/man3/scanf.3s, revision 1.1

1.1     ! root        1: .TH SCANF 3S  "19 January 1983"
        !             2: .SH NAME
        !             3: scanf, fscanf, sscanf \- formatted input conversion
        !             4: .SH SYNOPSIS
        !             5: .B #include <stdio.h>
        !             6: .PP
        !             7: .B scanf(format
        !             8: [ , pointer ] . . .
        !             9: .B )
        !            10: .br
        !            11: .B char *format;
        !            12: .PP
        !            13: .B fscanf(stream, format
        !            14: [ , pointer ] . . .
        !            15: .B )
        !            16: .br
        !            17: .SM
        !            18: .B FILE
        !            19: .B *stream;
        !            20: .br
        !            21: .B char *format;
        !            22: .PP
        !            23: .B sscanf(s, format
        !            24: [ , pointer ] . . .
        !            25: .B )
        !            26: .br
        !            27: .B char *s, *format;
        !            28: .SH DESCRIPTION
        !            29: .I Scanf
        !            30: reads from the standard input stream
        !            31: .BR stdin .
        !            32: .I Fscanf
        !            33: reads from the named input
        !            34: .IR stream .
        !            35: .I Sscanf
        !            36: reads from the character string
        !            37: .IR s .
        !            38: Each function reads characters, interprets
        !            39: them according to a format, and stores the results in its arguments.
        !            40: Each expects as arguments
        !            41: a control string
        !            42: .IR format ,
        !            43: described below,
        !            44: and a set of
        !            45: .I pointer
        !            46: arguments
        !            47: indicating where the converted input should be stored.
        !            48: .PP
        !            49: The
        !            50: control string
        !            51: usually contains
        !            52: conversion specifications, which are used to direct interpretation
        !            53: of input sequences.
        !            54: The control string may contain:
        !            55: .TP 4
        !            56: 1.
        !            57: Blanks, tabs or newlines,
        !            58: which match optional white space in the input.
        !            59: .TP 4
        !            60: 2.
        !            61: An ordinary character (not %) which must match
        !            62: the next character of the input stream.
        !            63: .TP 4
        !            64: 3.
        !            65: Conversion specifications, consisting of the
        !            66: character
        !            67: .BR % ,
        !            68: an optional assignment suppressing character
        !            69: .BR * ,
        !            70: an optional numerical maximum field width, and a conversion
        !            71: character.
        !            72: .PP
        !            73: A conversion specification directs the conversion of the
        !            74: next input field; the result
        !            75: is placed in the variable pointed to by the corresponding argument,
        !            76: unless assignment suppression was
        !            77: indicated by
        !            78: .BR * .
        !            79: An input field is defined as a string of non-space characters;
        !            80: it extends to the next inappropriate character or until the field
        !            81: width, if specified, is exhausted.
        !            82: .PP
        !            83: The conversion character indicates the interpretation of the
        !            84: input field; the corresponding pointer argument must
        !            85: usually be of a restricted type.
        !            86: The following conversion characters are legal:
        !            87: .TP 4
        !            88: .B  %
        !            89: a single `%' is expected
        !            90: in the input at this point;
        !            91: no assignment is done.
        !            92: .TP 4
        !            93: .B  d
        !            94: a decimal integer is expected;
        !            95: the corresponding argument should be an integer pointer.
        !            96: .TP 4
        !            97: .B  o
        !            98: an octal integer is expected;
        !            99: the corresponding argument should be a integer pointer.
        !           100: .TP 4
        !           101: .B  x
        !           102: a hexadecimal integer is expected;
        !           103: the corresponding argument should be an integer pointer.
        !           104: .ti -0.2i
        !           105: .TP 4
        !           106: .B  s
        !           107: a character string is expected;
        !           108: the corresponding argument should be a character pointer
        !           109: pointing to an array of characters large enough to accept the
        !           110: string and a terminating `\e0', which will be added.
        !           111: The input field is terminated by a space character
        !           112: or a newline.
        !           113: .TP 4
        !           114: .B  c
        !           115: a character is expected; the
        !           116: corresponding argument should be a character pointer.
        !           117: The normal skip over space characters is suppressed
        !           118: in this case;
        !           119: to read the next non-space character, try
        !           120: `%1s'.
        !           121: If a field width is given, the corresponding argument
        !           122: should refer to a character array, and the
        !           123: indicated number of characters is read.
        !           124: .TP 4
        !           125: \z\fBe\v'1'f\v'-1'\fR
        !           126: a
        !           127: floating point number is expected;
        !           128: the next field is converted accordingly and stored through the
        !           129: corresponding argument, which should be a pointer to a
        !           130: .IR float .
        !           131: The input format for
        !           132: floating point numbers is
        !           133: an optionally signed
        !           134: string of digits
        !           135: possibly containing a decimal point, followed by an optional
        !           136: exponent field consisting of an E or e followed by an optionally signed integer.
        !           137: .TP 4
        !           138: .B [
        !           139: indicates a string not to be delimited by space characters.
        !           140: The left bracket is followed by a set of characters and a right
        !           141: bracket; the characters between the brackets define a set
        !           142: of characters making up the string.
        !           143: If the first character
        !           144: is not circumflex (\|^\|), the input field
        !           145: is all characters until the first character not in the set between
        !           146: the brackets; if the first character
        !           147: after the left bracket is ^, the input field is all characters
        !           148: until the first character which is in the remaining set of characters
        !           149: between the brackets.
        !           150: The corresponding argument must point to a character array.
        !           151: .PP
        !           152: The conversion characters
        !           153: .BR d ,
        !           154: .B o
        !           155: and
        !           156: .B x
        !           157: may be capitalized or preceded by
        !           158: .B l
        !           159: to indicate that a pointer to
        !           160: .B long
        !           161: rather than to
        !           162: .B int
        !           163: is in the argument list.
        !           164: Similarly, the conversion characters
        !           165: .B e
        !           166: or
        !           167: .B f
        !           168: may be capitalized or
        !           169: preceded by
        !           170: .B l
        !           171: to indicate a pointer to 
        !           172: .B double
        !           173: rather than to 
        !           174: .BR float .
        !           175: The conversion characters
        !           176: .BR d ,
        !           177: .B o
        !           178: and
        !           179: .B x
        !           180: may be preceded by
        !           181: .B h
        !           182: to indicate a pointer to
        !           183: .B short
        !           184: rather than to
        !           185: .BR int .
        !           186: .PP
        !           187: The
        !           188: .I scanf
        !           189: functions return the number of successfully matched and assigned input
        !           190: items.
        !           191: This can be used to decide how many input items were found.
        !           192: The constant
        !           193: .SM
        !           194: .B EOF
        !           195: is returned upon end of input; note that this is different
        !           196: from 0, which means that no conversion was done;
        !           197: if conversion was intended, it was frustrated by an
        !           198: inappropriate character in the input.
        !           199: .PP
        !           200: For example, the call
        !           201: .IP "" 10
        !           202: int i; float x; char name[50];
        !           203: .br
        !           204: scanf("%d%f%s", &i, &x, name);
        !           205: .PP
        !           206: with the input line
        !           207: .IP
        !           208: 25   54.32E\(mi1  thompson
        !           209: .PP
        !           210: will assign to
        !           211: .I i
        !           212: the value
        !           213: 25,
        !           214: .I x
        !           215: the value 5.432, and
        !           216: .I name
        !           217: will contain
        !           218: .IR `thompson\e0' .
        !           219: Or,
        !           220: .IP
        !           221: int i; float x; char name[50];
        !           222: .br
        !           223: scanf("%2d%f%*d%[1234567890]", &i, &x, name);
        !           224: .PP
        !           225: with input
        !           226: .IP
        !           227: 56789 0123 56a72
        !           228: .PP
        !           229: will assign 56 to
        !           230: .IR i ,
        !           231: 789.0 to
        !           232: .IR x ,
        !           233: skip `0123',
        !           234: and place the string `56\e0' in
        !           235: .IR name .
        !           236: The next call to
        !           237: .I getchar
        !           238: will return `a'.
        !           239: .SH "SEE ALSO"
        !           240: atof(3),
        !           241: getc(3S),
        !           242: printf(3S)
        !           243: .SH DIAGNOSTICS
        !           244: The 
        !           245: .I scanf
        !           246: functions return
        !           247: .SM
        !           248: .B EOF
        !           249: on end of input,
        !           250: and a short count for missing or illegal data items.
        !           251: .SH BUGS
        !           252: The success of literal matches and suppressed
        !           253: assignments is not directly
        !           254: determinable.

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