Remove First and Last Character C++

Question

How to remove first and last character from std::string, I am already doing the following code.

But this code only removes the last character

m_VirtualHostName = m_VirtualHostName.erase(m_VirtualHostName.size() - 1)

How to remove the first character also?

Solution 1

Well, you could erase() the first character too (note that erase() modifies the string):

m_VirtualHostName.erase(0, 1);
m_VirtualHostName.erase(m_VirtualHostName.size() - 1);

But in this case, a simpler way is to take a substring:

m_VirtualHostName = m_VirtualHostName.substr(1, m_VirtualHostName.size() - 2);

Be careful to validate that the string actually has at least two characters in it first...

Solution 2

My BASIC interpreter chops beginning and ending quotes with

str->pop_back();
str->erase(str->begin());

Of course, I always expect well-formed BASIC style strings, so I will abort with failed assert if not:

assert(str->front() == '"' && str->back() == '"');

Just my two cents.

Comments

[Putra Fajar Hasanuddin]

it will crash, if im only have 2 characters ?

[Cameron]

@Putra: Yes. C++ is not particularly friendly that way ;-) Edit: No, I misread your comment. It will crash if you have less than two characters (0 or 1).

[Appleshell]

@PutraFajarHasanuddin It will when you have no or 1 character in the string. It's documented here. Only execute the second line when size() returns at least 1.

[David Rodríguez - dribeas]

While the substr looks cleaner in code it will trigger an additional memory allocation (which might or not be important). Also the first erase might be simpler if stated as: str.erase(str.end()-1); str.erase(str.begin());

[Mhadhbi issam]

this function make the string trimmed , it is equivalent to QString::trimmed(QString) , it delete the white space from end and front , do whatever it need to modify it to make it do the job ...............

[Brandlingo]

The while-loops (especially the front one) will make this quite inefficient. Search for the last/first blank and execute a single erase for each.

[Mhadhbi issam]

you can put the two condition in same while : as two condtion using AND or one while with if condition with break .