Manual Pages for UNIX Darwin command on man scan

scan(n) Tcl Built-In Commands scan(n)

NAME

scan - Parse string using conversion specifiers in the style of sscanf

SYNOPSIS

ssccaann string format ?varName varName ...? IINNTTRROODDUUCCTTIIOONN This command parses fields from an input string in the same fashion as

the ANSI C ssssccaannff procedure and returns a count of the number of con-

versions performed, or -1 if the end of the input string is reached

before any conversions have been performed. String gives the input to

be parsed and format indicates how to parse it, using %% conversion

specifiers as in ssssccaannff. Each varName gives the name of a variable;

when a field is scanned from string the result is converted back into a

string and assigned to the corresponding variable. If no varName vari-

ables are specified, then ssccaann works in an inline manner, returning the data that would otherwise be stored in the variables as a list. In the inline case, an empty string is returned when the end of the input string is reached before any conversions have been performed. DDEETTAAIILLSS OONN SSCCAANNNNIINNGG

SSccaann operates by scanning string and format together. If the next

character in format is a blank or tab then it matches any number of white space characters in string (including zero). Otherwise, if it

isn't a %% character then it must match the next character of string.

When a %% is encountered in format, it indicates the start of a conver-

sion specifier. A conversion specifier contains up to four fields |

after the %%: a **, which indicates that the converted value is to be |

discarded instead of assigned to a variable; a XPG3 position specifier; | a number indicating a maximum field width; a field size modifier; and a | conversion character. All of these fields are optional except for the conversion character. The fields that are present must appear in the order given above. When ssccaann finds a conversion specifier in format, it first skips any

white-space characters in string (unless the specifier is [[ or cc).

Then it converts the next input characters according to the conversion

specifier and stores the result in the variable given by the next argu-

ment to ssccaann.

If the %% is followed by a decimal number and a $$, as in ``%%22$$dd'', then

the variable to use is not taken from the next sequential argument. Instead, it is taken from the argument indicated by the number, where 1

corresponds to the first varName. If there are any positional speci-

fiers in format then all of the specifiers must be positional. Every varName on the argument list must correspond to exactly one conversion specifier or an error is generated, or in the inline case, any position can be specified at most once and the empty positions will be filled in with empty strings. The following conversion characters are supported: dd The input field must be a decimal integer. It is read in and the value is stored in the variable as a decimal string. If |

the ll or LL field size modifier is given, the scanned value |

will have an internal representation that is at least 64-bits |

in size. oo The input field must be an octal integer. It is read in and the value is stored in the variable as a decimal string. If |

the ll or LL field size modifier is given, the scanned value |

will have an internal representation that is at least 64-bits |

in size. If the value exceeds MAXINT (017777777777 on plat- |

forms using 32-bit integers when the ll and LL modifiers are |

not given), it will be truncated to a signed integer. Hence, |

037777777777 will appear as -1 on a 32-bit machine by |

default. xx The input field must be a hexadecimal integer. It is read in and the value is stored in the variable as a decimal string. |

If the ll or LL field size modifier is given, the scanned value |

will have an internal representation that is at least 64-bits |

in size. If the value exceeds MAXINT (0x7FFFFFFF on plat- |

forms using 32-bit integers when the ll and LL modifiers are |

not given), it will be truncated to a signed integer. Hence, |

0xFFFFFFFF will appear as -1 on a 32-bit machine.

uu The input field must be a decimal integer. The value is stored in the variable as an unsigned decimal integer string. |

If the ll or LL field size modifier is given, the scanned value |

will have an internal representation that is at least 64-bits |

in size. ii The input field must be an integer. The base (i.e. decimal, octal, or hexadecimal) is determined in the same fashion as described in eexxpprr. The value is stored in the variable as a decimal string. If the ll or LL field size modifier is given, |

the scanned value will have an internal representation that |

is at least 64-bits in size.

cc A single character is read in and its binary value is stored in the variable as a decimal string. Initial white space is

not skipped in this case, so the input field may be a white-

space character. This conversion is different from the ANSI standard in that the input field always consists of a single character and no field width may be specified. ss The input field consists of all the characters up to the next

white-space character; the characters are copied to the vari-

able. ee or ff or gg

The input field must be a floating-point number consisting of

an optional sign, a string of decimal digits possibly con-

taining a decimal point, and an optional exponent consisting of an ee or EE followed by an optional sign and a string of decimal digits. It is read in and stored in the variable as

a floating-point string.

[[chars]] The input field consists of any number of characters in chars. The matching string is stored in the variable. If the first character between the brackets is a ]] then it is treated as part of chars rather than the closing bracket for

the set. If chars contains a sequence of the form a-b then

any character between a and b (inclusive) will match. If the

first or last character between the brackets is a -, then it

is treated as part of chars rather than indicating a range. [[^^chars]] The input field consists of any number of characters not in chars. The matching string is stored in the variable. If the character immediately following the ^^ is a ]] then it is treated as part of the set rather than the closing bracket

for the set. If chars contains a sequence of the form a-b

then any character between a and b (inclusive) will be excluded from the set. If the first or last character

between the brackets is a -, then it is treated as part of

chars rather than indicating a range. nn No input is consumed from the input string. Instead, the

total number of characters scanned from the input string so

far is stored in the variable. The number of characters read from the input for a conversion is the largest number that makes sense for that particular conversion (e.g.

as many decimal digits as possible for %%dd, as many octal digits as pos-

sible for %%oo, and so on). The input field for a given conversion ter-

minates either when a white-space character is encountered or when the

maximum field width has been reached, whichever comes first. If a ** is present in the conversion specifier then no variable is assigned and

the next scan argument is not consumed.

DDIIFFFFEERREENNCCEESS FFRROOMM AANNSSII SSSSCCAANNFF The behavior of the ssccaann command is the same as the behavior of the ANSI C ssssccaannff procedure except for the following differences:

[1] %%pp conversion specifier is not currently supported.

[2] For %%cc conversions a single character value is converted to a

decimal string, which is then assigned to the corresponding var-

Name; no field width may be specified for this conversion. [3] The hh modifier is always ignored and the ll and LL modifiers are | ignored when converting real values (i.e. type ddoouubbllee is used | for the internal representation). [4] If the end of the input string is reached before any conversions have been performed and no variables are given, an empty string is returned.

format(n), sscanf(3)

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