Lec-02-BWN - Lecture 02 ECE364 Software Tools Laboratory...

9/1/2009
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ECE364: Software Tools
Laboratory
Lecture 2
August 31, 2009
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Lecture 02
 Indexed arrays
 Additional KornShell functionality
 Basic regular expressions
 Quotes
 Shell commands
 Case statement
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Arrays in ksh
 An array can be declared with:
Arr=(1 2 3 4 foo)
set -A Arr 1 2 3 4 foo
 You can access an array like so:
$ print ${Arr[2]}
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$ print ${Arr[*]}
1 2 3 4 foo
 You can assign individual elements too (the
index will be added if it doesn't exist):
Arr[5]="hi there"
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Arrays in ksh
 Unlike C, ksh supports sparse arrays
Sparse[5]=8
Sparse[15]=12
Sparse[19]=7
 If the indices aren't consecutive, how do
we know the array's size? How do we
know the indices for all values?
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Special operators # and !
 You can obtain a list (a string of whitespace-
separated values) of every element in an
array:
print ${Array[*]}
print ${Array[@]}
 The size of an array can be found by using
the
#
operator:
${#Array[*]} or ${#Array[@]}
 The array subscripts can be found by using
the
!
operator:
${!Array[*]} or ${!Array[@]}
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Indexed array example
#! /bin/ksh
A[5]=34
A[1]=3
A[2]=56
A[100]=89
print "Size of array: ${#A[*]}"
print "Array indices: ${!A[*]}"
for I in ${!A[*]}
do
print "A[${I}]=${A[I]}"
done
exit 0
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9/1/2009
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Indexed array output
Size of array: 4
Array indices: 1 2 5 100
A[1]=3
A[2]=56
A[5]=34
A[100]=89
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Read array example
#! /bin/ksh
print "Data_File:"
cat Data_File
print
print "Formatted output:"
while read -A Data # Split on whitespace
do # (spaces and tabs)
for Item in ${Data[*]}
do
printf "%6.2f\n" $Item
done
done < Data_File
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Output
Data_File:
1 2 3 77
12 12.6 6.8 7
2 1.0 -3 -5.5
Formatted output
1.00 2.00 3.00 77.00
12.00 12.60 6.80 7.00
2.00 1.00 -3.00 -5.50
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Binary operators
 You remember our friends from ECE 264,
right?
<< n
Shift left n bits
>> n
Shift right n bits
&
Bitwise AND
^
Bitwise EXCLUSIVE OR
|
Bitwise OR
~
Bitwise negation
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Binary operations
#! /bin/ksh
integer A=2#1101
integer B=2#0110
integer C
(( C = A & B ))
print "(( C = $A & $B )) C = $C"
(( C = A | B ))
print "(( C = $A | $B )) C = $C"
(( C = A ^ B ))
print "(( C = $A ^ $B )) C = $C"
exit 0
Results (the values actually displayed are in base 10):
(( C = 2#1101 & 2#110 )) C = 2#100
(( C = 2#1101 | 2#110 )) C = 2#1111
(( C = 2#1101 ^ 2#110 )) C = 2#1011
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More binary operations
#! /bin/ksh
integer A=2#1101
integer B=2#0110
integer C
(( C = A << 2 ))
print "(( C = $A << 2 )) C = $C"
(( C = B >> 1 )) (( C B >> 1 ))
print "(( C = $B >> 2 )) C = $C"
(( C = ~B ))
print "(( C = ~$B )) C = $C"
exit 0
Results in:
(( C = 2#1101 << 2 )) C = 2#110100
(( C = 2#110 >> 1 )) C = 2#11
(( C = ~2#110 )) C = 2#11111111111111111111111111111001
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