Question

Comrades,

The following does not work:

vector<string>::iterator c;

for( c = holdtype.begin(); c != holdtype.end(); c++)
{ 
    if( *c == "preposition" )
    {
        c++; 
        if( *c == "unknown" )
        {       
            c++;  
            if( *c == "unknown" )
            {
                c++;  
                if( *c == "unknown" )
                {
                    cout <<endl <<"This should be a verb " << *c;
                }
            }
        }
    } 
}

The strange thing is that it works for a certain amount of data. As soon as it goes above roughly 30 words it stops working and gives me the “not dereferencable error”.

I have tried this and it gives the same results:

vector<string>::iterator c;
c = holdtype.begin();

while( c != holdtype.end())
{ 
    if( *c == "preposition" )
    {
        if( c != holdtype.end() ) { c++; } else { break; }
        if( *c == "unknown" )
        {       
            if( c != holdtype.end() ) { c++; } else { break; }
            if( *c == "unknown" )
            {
                if( c != holdtype.end() ) { c++; } else { break; }
                if( *c == "unknown" )
                {
                    cout <<endl <<"This should be a verb " << *c;
                }
            }
        }
    } 
    if( c == holdtype.end() ) { break; } else {c++;}
}

I have been trying to figure this out for a few days now, I am a beginner.

Answer 1

Your second version is almost correct, but you need to check if c is valid after you increment and before you dereference:

vector<string>::iterator c;
c = holdtype.begin();

while( c != holdtype.end())
{ 
    if( *c == "preposition" )
    {
        ++c;
        if( c == holdtype.end() ) { break; }
        if( *c == "unknown" )
        {       
            ++c;
            if( c == holdtype.end() ) { break; }
            if( *c == "unknown" )
            {
                ++c;
                if( c == holdtype.end() ) { break; }
                if( *c == "unknown" )
                {
                    cout <<endl <<"This should be a verb " << *c;
                }
            }
        }
    } 
    ++c;
}