using '?' conditional with for loop

[Cambalinho]

see these line:
for (unsigned int index=blnFunction? 2 : 1 , varcount=1; index< blnFunction? ...
i don't get any compiler errors, but when i execute it, the exe give me an error(like an exit error)..
but if i use the parentheses, will works normaly:
for (unsigned int index=(blnFunction? 2 : 1) , varcount=1; index< (blnFunction? CodeLine.size(): CodeLine.size()-1);...
why the compiler don't give me an error\warning about using it with or without parenthese?

[Repeater]

You're completely changing the meaning by adding those parenthese.

First, did you actually mean = , or did you mean == ?

What are you trying to do with index? Are you trying to set it equal to blnFunction, or are you trying to set it to the value 2 or 1, depending on blnFunction?

[coder777]

The keyword here is precedence of operators. See:

http://www.cplusplus.com/doc/tutorial/operators/

The ?: has a very low precedence.

[Cambalinho]

thank for correct me Coder777.
Repeater: the index value depends on blnFunction value.

for(initialvalue; condition; increment)
increment or decrement, it depends what order we need

but like Coder777 said, and makes sence is the precedence of operators.
thanks to all

[JLBorges]

> why the compiler don't give me an error\warning about using it

Some compilers do warn you if warnings are enabled.

int main()
{
    extern bool b ;
    for( int i = b ? 2 : 1 , v = 1 ; i < b ? 10 : 20 ; ++i, ++v )  ;
    
    // GNU (-Wall -Wextra):
    //  warning: ?: using integer constants in boolean context, the expression will always evaluate to 'true' [-Wint-in-bool-context]
    // 5 |     for( int i = b ? 2 : 1 , v = 1 ; i < b ? 10 : 20 ; ++i, ++v )  ;
    //   |                                      ~~~~~~^~~~~~~~~
    
    // Microsoft (-W4):
    //  warning C4804: '<': unsafe use of type 'bool' in operation
}

http://coliru.stacked-crooked.com/a/0e9bbad9f4692a57
https://rextester.com/LYDD97379

Perhaps the more important question: why do you want to write this kind of code?

[Cambalinho]

"Perhaps the more important question: why do you want to write this kind of code?"

 void RulesVar(vector<TokensType> CodeLine, unsigned int intCodeLine, bool blnFunction=false)
    {
        //var [const] VarName [as VarType [= VarValue]]
        if( CodeLine.size()==1)
        {
            ErrorList.push_back({"Var creation error!!!", "You must give a var name!!!", 0, intCodeLine});
        }
        bool blnConst=false;
        bool blnArray=false;
        bool blnArraySize=false;
        for (unsigned int index=(blnFunction? 2 : 1), varcount=1; index<blnFunction? CodeLine.size(): CodeLine.size()-1; index++, varcount++)
        {
            if(CodeLine[index].Token=="[")

is for i see where i must start and where i must stop

[JLBorges]

Something like this, perhaps:

std::size_t index = 1 + blnFunction ; // blnFunction ? 2 : 1
const std::size_t ubound = CodeLine.size()-1 + blnFunction ; // blnFunction ? CodeLine.size() : CodeLine.size()-1
for( ; index < ubound ; ++index )
{
    // if( CodeLine.at(index) ) etc.
    // ...
}

const std::size_t varcount = index - blnFunction ;

[Cambalinho]

true.... thanks