I would think the simplest way to handle this would be to add an additional condition inside your pre-existing condition (that is not related to Obama Care ) to test if "n2" is 0 (zero) before you attempt to divide by it:
Code:
elif [ $opr = "4" ]
then
... test if n2 is zero, if not, do this...
echo $((n1/n2))
... else do this
fi
e.g.
Code:
...
elif [ $opr = "4" ]
then
if [ "$n2" != 0 ]; then # for numbers, normally, you would use "-ne" (not equal to) in place of "!=", but you didn't sanitise the input
echo $((n1/n2))
else
echo "Divide by zero"
fi
fi
...
If the intention is not to show that you are dividing by zero, but to prevent it doing so altogether, you can amend the existing elif that handles that case to also check that "n2" is not zero. Talking of which, it may be better (simpler) to use a "case" statement instead of "if" - ifs can get a bit clumsy looking, when there's lots of elifs going on.
Hey can anyone tell me the korn script code to implement an interactive integer calculator using the shell's built in arithemetic expression evaluation (2 Replies)
I am pretty new to the Unix word, and have created a working calculator script. I have one problem. It doesn't use any decimals, it rounds off to the nearest whole number.
1 #!/bin/ksh
2 while true; do
3 echo -n "Enter the first integer: "; read IN1
4 test... (2 Replies)
hi, im new to the unix system and scripting and was wondering if anyone could help me with this problem iv been havin... i want the system to:
1. ask me for a number
2. ask me for a command to use on that number (* + - /)
3. ask me for another number
4. then ask me for another command, if the... (2 Replies)
I have 2 questions.
1) Is there a means of directing output to a file (">") while making it still output to the console?
I have a script that calls another lengthy script.
2) I can direct the output of the lengthy script and grep it for the words "good" or "bad" to know if I need the run... (2 Replies)
Hi Guys,
I found this code in net.. it is working fine..
But can anybody explain me the sed statement used in the code..
echo "Enter the expression:\c"
read express
eval echo "$express"|sed 's/^/'$precision' \
/'|bc -l|\
sed -n '1,${
/syntax/!{
}
... (2 Replies)
hi,
I have some problems in my simple script about the redirect echo stdout command inside a condition. Why is the echo command inside the elif still execute in the else command
Here are my simple script
After check on the two diff output the echo stdout redirect is present in two diff... (3 Replies)
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known/data:
Script a simple calculator. In the command line enter the script file
/home/etc/mycalc or /home/etc/mycalc 1 +... (6 Replies)
HI
My doubt may be basic one but I need to get it clarified..
When i use "if" condition that checks for many AND, OR logical conditions
like
if ]; then
return 0
fi
Even the if condition fails it returns as zero.. Any clue..
But if i add else condition like
if ]; ... (2 Replies)
I wrote a code to find codons in a DNA string. The only problem I have is how do I make the code only work for a file with DNA. This means the file only has the characters a,c,g,t and no white space characters. (3 Replies)
So have I got this :
#!/bin/bash
clear
echo "Enter the first number:"
read n1
echo "Choose an operation:"
echo "1. add"
echo "2. subtract"
echo "3. multiply"
echo "4. divide"
read opr
echo "Enter the second number:"
read n2 (1 Reply)
Discussion started by: mugiboya
1 Replies
LEARN ABOUT OSF1
unifdef
unifdef(1) General Commands Manual unifdef(1)NAME
unifdef - Removes #ifdefed lines
SYNOPSIS
unifdef [-tlc] [-Dsymbol] [-idsymbol] [-iusymbol] [file] [-Usymbol]
The unifdef command partially simulates the behavior of the C preprocessor in processing #ifdef conditionals.
OPTIONS
Complements the action of unifdef; retains lines that would normally be removed and removes lines that would normally be retained. Speci-
fies symbol as a defined #ifdef symbol. Specifies defined lines inside certain #ifdefs to be ignored but copied out. Specifies undefined
lines inside certain #ifdefs to be ignored and not copied out. Replaces removed lines with blank lines instead of deleting them. Pro-
cesses plain text (rather than C code) input. The unifdef command does not try to recognize comments, single quotes, and double quotes.
Specifies symbol as an undefined #ifdef symbol.
DESCRIPTION
The unifdef command recognizes nested #ifdefs, comments, single and double quotes of C syntax so that it can function correctly, but does
not include files or interpret macros. The unifdef command recognizes, but does not remove comments.
The unifdef command takes its input from stdin if no file argument is given, and copies its output to stdout.
You specify the symbols you want defined with -Dsymbol or undefined with -Usymbol and the lines inside those #ifdefs are copied to the out-
put or removed, as appropriate. The #ifdef, #ifndef, #else, #elif, and endif lines associated with symbol are also removed. The #ifdefs
involving unspecified symbols are untouched and copied out along with their associated #ifdef, #else, elif, and #endif lines. If the same
symbol appears in more than one argument, only the first occurrence is significant. For instance, if an #ifdef X occurs nested inside
another #ifdef X, the inside #ifdef is considered an unrecognized symbol.
If you use #ifdefs to delimit non-C lines, such as comments or unfinished code, it is necessary to specify which symbols are to be used for
that purpose. Otherwise, the unifdef command tries to parse for quotes and comments in those #ifdef lines.
Keywords
The following keywords can be used with the unifdef command:
ifdef ifndef else endif elif
The unifdef command uses the elif keyword as follows. (Note that "Understood" means unifdef knows how to convert elif to if.) Understood
Not understood Not understood
For example:
# ifdef X x # elif defined (Y) y # elif defined (A) || defined (B) a # else default # endif
The following list shows the results of using the elif keyword with variables:
-DX x
-UX # if defined (Y) y # elif defined (A) || defined (B) a # else default # endif -UX -DY y
-UY -UX # if defined (Y) y # elif defined (A) || defined (B) a # else default # endif
-UY -UX -DA # if defined (Y) y # elif defined (A) || defined (B) a # else default # endif
NOTES
The unifdef command cannot process cpp constructs such as:
#if defined(X) || defined(Y)
DIAGNOSTICS
The unifdef command can fail for several reasons: a premature end of file, or an inappropriate else, elif, or endif.
EXIT STATUS
Exit status is 0 if output is an exact copy of input, 1 if not, 2 if the unifdef command fails.
EXAMPLES
The following command line causes the unifdef command to read the file original.c and remove the #ifdef A lines. It then removes every-
thing following an #elif/#else associated with the #ifdef A down to the #endif: unifdef -DA original.c > modified.c The following command
line causes the unifdef command to read the file original.c, and remove the #ifdef A down to either its associated #elif/#else, or its
associated #endif: unifdef -UA original.c > modified.c
In the case of the #elif, the #elif is replaced with #if. In the case of #else, the #else is deleted along with its associated
#endif.
SEE ALSO
Commands: diff(1)unifdef(1)
11-20-2017
) to test if "n2" is 0 (zero) before you attempt to divide by it: