Isogram challenge c++ - answered, thank you.

Question

Could anyone give me a tip on how to solve the Isogram challenge in c++? I‘ve been trying different things for the last three hours and still couldn‘t manage to solve the problem.
For instance, this little bit of code gives me the following warning: comparison of integer expressions of different signedness “int” and “std::...” although many examples I found online suggest exactly this approach.?

Code bit:

(before string declared)

for (int i = 0; i < string.length(); i++)
{

for (int j = i+1; j < string.length(); j++)
{

if (string[i] == string[j])
{return false;
}
}
}

and so on...

Thanks for any ideas!

Answer 1

string.length returns an std::.....
unsigned int or sth. like this. Try:
for(unsigned int i=0;........)
This would be better as string length is ever positive....
Moreover you can just ignore some warnings