scan(3Tcl) scan(3Tcl)
scan - Parse string using conversion specifiers in the style of sscanf
scan string format varName ?varName ...?
This command parses fields from an input string in the same fashion as
the ANSI C sscanf procedure and returns a count of the number of |
conversions 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 sscanf. 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.
DETAILS ON SCANNING
Scan operates by scanning string and formatString together. If the next
character in formatString 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 formatString, it indicates the start of a
conversion specifier. A conversion specifier contains three fields after
the %: a *, which indicates that the converted value is to be discarded
instead of assigned to a variable; a number indicating a maximum field
width; and a conversion character. All of these fields are optional
except for the conversion character.
When scan finds a conversion specifier in formatString, it first skips
any white-space characters in string. Then it converts the next input
characters according to the conversion specifier and stores the result in
the variable given by the next argument to scan. The following
conversion characters are supported:
d The input field must be a decimal integer. It is read in and
the value is stored in the variable as a decimal string.
o The input field must be an octal integer. It is read in and the
value is stored in the variable as a decimal string.
x The input field must be a hexadecimal integer. It is read in
and the value is stored in the variable as a decimal string.
c 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.
Page 1
scan(3Tcl) scan(3Tcl)
s The input field consists of all the characters up to the next
white-space character; the characters are copied to the
variable.
e or f or g
The input field must be a floating-point number consisting of
an optional sign, a string of decimal digits possibly
containing a decimal point, and an optional exponent consisting
of an e or E 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.
[^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.
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 %d, as many octal digits as possible
for %o, and so on). The input field for a given conversion terminates
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.
DIFFERENCES FROM ANSI SSCANF [Toc] [Back] The behavior of the scan command is the same as the behavior of the ANSI
C sscanf procedure except for the following differences:
[1] %p and %n conversion specifiers are not currently supported. |
[2] For %c conversions a single character value is converted to a
decimal string, which is then assigned to the corresponding varName;
no field width may be specified for this conversion.
[3] The l, h, and L modifiers are ignored; integer values are always |
converted as if there were no modifier present and real values are |
always converted as if the l modifier were present (i.e. type double|
is used for the internal representation).
conversion specifier, parse, scan
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SCAN(3I) Last changed: 1-6-98
SCAN - Scans a string for any one of the characters in a set of
characters
SCAN ([STRING=]string, [SET=]set [,[BACK=]back])
UNICOS, UNICOS/mk, and IRIX systems
Fortran 90
The SCAN intrinsic function scans a string for any one of the
characters in a set of characters. It accepts the following
arguments:
string Must be of type character.
set Must be of type character.
back Must be of type logical. If back is omitted, a value of
false is assumed.
SCAN is an elemental function. The name of this intrinsic cannot be
passed as an argument.
SCAN returns the character position of the first character in string
that matches any characters in set. The result is a default integer.
If back is absent or present with value false and if string contains
at least one character that is in set, the value of the result is the
position of the leftmost character of string that is in set.
If back is present with the value true, and if string contains at
least one character that is in set, the value of the result is the
position of the rightmost character of string that is in set.
SCAN returns zero if no character in string is in set, or if the
length of string is zero.
Example 1: The statement SCAN('FORTRAN', 'TR') returns the value 3.
Example 2: The statement SCAN('FORTRAN', 'TR', BACK=.TRUE.) returns
the value 5.
Example 3: The statement SCAN('FORTRAN', 'BCD') returns the value 0.
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
SCAN(3I) Last changed: 1-6-98
SCAN - Scans a string for any one of the characters in a set of
characters
SCAN ([STRING=]string, [SET=]set [,[BACK=]back])
UNICOS, UNICOS/mk, and IRIX systems
Fortran 90
The SCAN intrinsic function scans a string for any one of the
characters in a set of characters. It accepts the following
arguments:
string Must be of type character.
set Must be of type character.
back Must be of type logical. If back is omitted, a value of
false is assumed.
SCAN is an elemental function. The name of this intrinsic cannot be
passed as an argument.
SCAN returns the character position of the first character in string
that matches any characters in set. The result is a default integer.
If back is absent or present with value false and if string contains
at least one character that is in set, the value of the result is the
position of the leftmost character of string that is in set.
If back is present with the value true, and if string contains at
least one character that is in set, the value of the result is the
position of the rightmost character of string that is in set.
SCAN returns zero if no character in string is in set, or if the
length of string is zero.
Example 1: The statement SCAN('FORTRAN', 'TR') returns the value 3.
Example 2: The statement SCAN('FORTRAN', 'TR', BACK=.TRUE.) returns
the value 5.
Example 3: The statement SCAN('FORTRAN', 'BCD') returns the value 0.
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
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