Delete characters form a string in C++ [closed] - c++

Question

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist
Closed 9 years ago.
Improve this question
I'm beginning in C++ and I have a simple task. As title said, I want to delete first and last character from a string for x times (where x is the lenght of the string). For example, if the string is "example", the result will be:
example
xampl
amp
m
amp
xampl
example
So far, I'm thinking like this:
#include <iostream>
#include <string>
string sir = "Example";
int len, i;
len = sir.length();
for(i=1; i<=len; i++)
{
sir.erase(sir.begin(), sir.end());
cout<<sir;
}
Or something like that... Can someone help me ?

Answer 1

You want to delete both the first and last char.But in the example you also added them each step. It is not actually clear what you want. Whatever you want to delete or add the characters it is feasible to keep the string unchanged. So you should use substr. Check it out here.

Answer 2

The problem is that
you can not use std::string::erase with integral index such as int i,
you need to use std::string::iterator
but even if you use std::string::iterator, with the current logic you would be trying to increment an iterator after the erase has been called. (such iterator is invalid)
Possible solution: assign sir.begin() to your iterator after each erase.
Here's how it could look like:
std::string sir = "Example";
for(string::iterator i = sir.begin(); i != sir.end(); i = sir.begin())
{
sir.erase(i);
std::cout << sir << std::endl;
}
outputs:
xample
ample
mple
ple
le
e
Just note that after erasing characters from your std::string, these characters are lost. You can not "restore" them. For the other half, you'll have to come with more sophisticated approach, but I'll leave that to you :)