Shell Programming and Scripting

Hi all,
If anyone has the explanation for the following issue, please share it with me.

I am comparing two variable a and b with the values of 007 and 7, for these values it get evaluated as True. For a=008 and b=8, for these values it get evaluated as false.

#!/bin/tclsh
set a 007
set b 7
if { $a == $b } {
puts "$a equals to $b"
} else {
puts "$a not equals to $b"
}
set a 008
set b 8
if { $a == $b } {
puts "$a equals to $b"
} else {
puts "$a not equals to $b"
}

Output:
007 equals to 7
008 not equals to 8

In Fact a = (001,002,...007) and b= (1,2,...7) it get evaluated as True and becomes false for a > 007 and b > 7.

Thanks
Sarwan

I'm not familiar with tclsh so I'm not sure about it, but it seems that it evalutes a value with a preceding 0 as an octet value.

Regards

The observed behaviour is correct.

Changing the value of a to 010 (octal 10) in the second part of your example will cause the if statement to evaluate to true.

Code:

set a 010
set b 8

if { $a == $b } {
   puts "$a equals to $b"
} else {
   puts "$a not equals to $b"
}

Hi fpmurphy and Franklin thanks for the answer. As per my program a and b are integers, "a" is not a octal, but I will get "a" as preceeded by 0, like 001,002,..008.. and "b" like 1,2...8...10. So now I had modified the program as follows.

set a 008
set b 8

if { [string length $b] == 1 } {
set b "00$b"
} elseif { [string length $b] == 2 } {
set b "0$b"
}

if { $a == $b } {
puts "$a equals to $b"
} else {
puts "$a not equals to $b"
}

Output:
008 equals to 008