NSIS variable value get set concerns

Question

Well, from few years I'm working with NSIS installers and I treat all variables as string in my scripts. Somewhere I read about this, that NSIS internally treat all variables as string, but don't know the exact fact.

Now my query is whenever we are copying some values into some variables or checking the variable's value using logic statements what should be the ideal way to do it. Let me show you an example what I'm talking about.

StrCpy $1 "Some string goes here"
StrCpy $2 999

${If} $1 == "String to match here"

${If} $2 == 999

${If} $2 == "999"

I guess I have no other option for StrCpy $1 case as there I'm copying string into a variable, but for case StrCpy $2, perhaps I can write StrCpy $2 "999" as well. Same thing goes for If statements.

I would like to know the correct convention for NSIS scripting.

Anders Anders · Accepted Answer · 2015-05-22T14:49:19

Yes, internally everything is stored as strings and they converted to numbers when doing a number operation. Strings that cannot be converted to numbers are treated as 0.

StrCpy $2 999 and StrCpy $2 "999" is exactly the same thing, the quotes are only required when the string has spaces and the quotes are removed by the compiler automatically even when there are no spaces. This also means that ${If} $2 == 999 and ${If} $2 == "999" is the same.

When comparing you should use =, <>, <, <=, >= and > for numbers and == and != for strings.

${IfThen} 0x29A = 666 ${|} DetailPrint "True" ${|} ; 0x29A is 666 in hex
${IfThen} 0x29A == 666 ${|} DetailPrint "This will never print" ${|}

NSIS variable value get set concerns

1 Answers