Is there a foolproof way to enter single quotes (') in a Control Language (CL) program variable without having to double them?

Nearly everyone knows that to embed a quotation mark in a CL variable you have to double it. To putNAME='SMITH'in a variable, you have to enter'NAME=''SMITH'''. Enter an uneven number of quote marks and the CL prompter will attempt, and nearly always fail, to fix if for you, which can make entering code challenging and sometimes frustrating. What if we could use a double quote ("), and then easily replace each with a single quote programmatically?

A recent discussion got me wondering if there was, indeed, an easier way. I did some coding, research, and experimentation and came up with two experimental commands:

• FIXQTE replaces each double quote character in a CL variable with a single quote character.
• RPLSTR replaces one string in a CL variable with another string.

This article documents my findings and alternative ways to put single quotes in CL variables.

Article definitions:

• "Quote" means one character (') which is sometimes described as an apostrophe or a tick.
• "Double quote" also means one character ("), which is sometimes described as a quotation mark. Do not confuse it with two single quotes ('').

A Problem Example

Here's an example of the quote conundrum. You are trying to put quotes around a variable, perhaps to use it in an SQL WHERE statement:

(&sel *bcat '''' *bcat &name *bcat '''')

Miscount the single quotes and the CL prompter might helpfully change it to this:

('(&SEL *BCAT '''''' *BCAT &NAME *BCAT '''''''')')

What's the best approach to avoid this confusion while making such entries? A discussion of possible approaches follows.

Approach 1: Live with It and Code Carefully

Understand when you need to double the quote, and then enter code carefully. To evaluate ease of entry and readability, I created a test CL program T1 with two entered parameters (Figure 1, below). The program has to build an SQL statement with a "where" clause from the parameters, run the SQL, and display the results. The input file is on virtually all IBM i machines, if you want to compile and run it.

Calling the program thus…

call t1 ('ON' 'NY')

creates an SQL statement in a variable that has embedded quotes, like this:

create table qtemp/zz as (select * from qiws/qcustcdt

where upper(lstnam) like '%ON%' and state='NY'

order by lstnam) with data

Running it displays two records:

0001.00 pgm parm(&name &state)                                        

0002.00 dcl &name *char 10 'ON'                                      

0003.00 dcl &state *char 2 'NY'                                      

0004.00 dcl &sql *char 512 'create table qtemp/zz as ('              

0005.00 dcl &sel *char 100 'select * from qiws/qcustcdt where '      

0006.00 dcl &whr *char 256                                            

0007.00 dcl &end *char 50 'order by lstnam) with data'              

0008.00 chgvar &whr ('upper(lstnam) like ''%' *tcat &name *tcat '%''')

0009.00 chgvar &whr (&whr *tcat 'and state=''' *tcat &state *tcat '''')

0010.00 chgvar var(&sql) value(&sql *tcat &sel *bcat &whr *bcat &end)

0011.00 sndmsg &sql tousr(*requester)                                

0012.00 runsql &sql commit(*none)                                      

0013.00 runqry *none qtemp/zz                                        

0014.00 dltf qtemp/zz                                                

0015.00 endpgm                                                        

Figure 1: Program T1, coded carefully

Where you can come undone is entering line 8, building the &whr variable. On the right side, the string must be in quotes, but we need to embed quotes around the &name field, as well as around the % sign at each end of the &name value. These quotes, inside the enclosing outer quotes, have to be doubled. Similarly with adding the state selection in line 9. But, by being careful, you can get it done.

Approach 2: Quote Variables Separately

First put quotes around each parameter value, and use these quoted variables in the right side. We introduce two new longer variables to hold the quotes on each end of the variable. And for name, we also need space for the % signs. We create program T2 by making the changes in Figure 2, below, to program T1.

0008.00 dcl &qname *char 14                                

0009.00 dcl &qstate *char 4                                

0010.00 chgvar &qname ('%' *tcat &name *tcat '%')        

0011.00 chgvar &qname ('''' *tcat &qname *tcat '''')    

0012.00 chgvar &qstate ('''' *tcat &state *tcat '''')    

0013.00 chgvar &whr ('upper(lstnam) like' *bcat &qname)  

0014.00 chgvar &whr (&whr *tcat 'and state=' *tcat &qstate)

Figure 2: Changes to T1 to make program T2

This makes lines 13 and 14 simpler to enter and easier to read, and we've avoided embedding quotes in the right side. The downside is two extra lines of code for each quoted variable.

Approach 3: Use a Variable for the Quote

Declare a single character viable that is a quote and use that where you need to embed a quote. Change program T1 as in Figure 3 below to create program T3.

0008.00 dcl &qt *char 1 ''''   /* single quote */            

0009.00 chgvar &whr ('upper(lstnam) like ' *tcat &qt *tcat '%')

0010.00 chgvar &whr (&whr *tcat &name *tcat '%' *tcat &qt)    

0011.00 chgvar &whr (&whr *bcat 'and state=' *tcat &qt)      

0012.00 chgvar &whr (&whr *tcat &state *tcat &qt)            

Figure 3: Changes to T1 to make program T3

It is harder to miscount quotes, but to me, it seems less readable.

Approach 4: A Combination of 2 and 3

This means minor changes to T2 to make program T4, as in Figure 4.

0008.00 dcl &qname *char 14                      

0009.00 dcl &qstate *char 4                      

0010.00 dcl &qt *char 1 ''''   /* a single ' */  

0011.00 chgvar &qname ('%' *tcat &name *tcat '%')

0012.00 chgvar &qname (&qt *tcat &qname *tcat &qt)

0013.00 chgvar &qstate (&qt *tcat &state *tcat &qt)

Figure 4: Changes to T2 to make program T4

This adds a little to the readability and decreases the chance of miscounting quotes.

Approach 5: Use the FIXQTE Command

Where you need two quotes to create a single embedded quote, enter a single double quote instead and convert to single quotes at run time. We create program T5 by changing T1 as in Figure 5 below:

0008.00 chgvar &whr ('upper(lstnam) like "%' *tcat &name *tcat '%"')

0009.00 chgvar &whr (&whr *tcat 'and state="' *tcat &state *tcat '"')

0010.00 chgvar &sql (&sql *tcat &sel *bcat &whr *bcat &end)

0011.00 fixqte &sql                                                  

Figure 5: Changes to T1 to make program T5

The FIXQTE command in line 11 changes all occurrences of " to ' in the &sql variable. It eases entry and improves readability.

Approach 6: Use FIXQTE and Quote Variables Separately

This is a minor tweak of program T2. The changes are shown in Figure 6.

0010.00 chgvar &qname ('%' *tcat &name *tcat '%')        

0011.00 chgvar &qname ('"' *tcat &qname *tcat '"')      

0012.00 chgvar &qstate ('"' *tcat &state *tcat '"')      

0013.00 chgvar &whr ('upper(lstnam) like' *bcat &qname)  

0014.00 chgvar &whr (&whr *tcat 'and state=' *tcat &qstate)

0015.00 chgvar &sql (&sql *tcat &sel *bcat &whr *bcat &end)

0016.00 fixqte &sql                                      

Figure 6: Changes to program T2 to make program T6

My Conclusion

After coding and experimenting, I've decided that coding embedded quotes in CL variables may always be tricky. Having a clear view of the string you are building is important so you know where embedded quotes are needed.

For most of my career, I've tended to use Approach 2, where I put the quotes around the variable before building the final string. Sometimes I've felt clever and opted to code carefully, and often pounded the keyboard when I miscounted the quotes. FIXQTE should reduce such pounding and also improve readability if you choose not to quote variables separately.

You may have another approach to embedding quotes that you'd like to share. I'm all ears.

 The FIXQTE and RPLSTR Commands

These both call the same RPG program that replaces a string in a CL program character variable with another string. FIXQTE simply defaults to replacing " with '. RPLSTR allows you to specify the from and the to strings.

A RPLSTR example:

0001.00 pgm                                              

0002.00 dcl &logmsg *char 50 ('Using \TorP\ library list')

0003.00 rplstr (&LOGMSG) FROM('\TorP\') TO(PRODUCTION)  

0004.00 sndmsg &logmsg tousr(*requester)                

0005.00 endpgm                                          

A call results in this message being sent:

Using PRODUCTION library list

Code

The code for the commands, the program, and the sample approach code is available for download here. For completeness, I have included help for the commands. The RPG program uses the %SCANRPL function introduced in V7R1 and tested on V7R4.

Sam Lennon is an analyst, developer, consultant and IBM i geek. He started his programming career in 360 assembly language on IBM mainframes, but moved to the AS400 platform in 1991 and has been an AS400/iSeries/i5/IBM i advocate ever since.