CODEWITHSUNDEEP
c++c++11stl-algorithm
Pdksock
Pdksock

Reputation: 1030

remove_copy usage with strings

My string is !!(!()). I want to remove double exclamation from the string.

This works but it removes all exclamations

remove_copy(str.begin(), str.end(),ostream_iterator<char>(cout), '!');//gives (())

This does not work

remove_copy(str.begin(), str.end(),ostream_iterator<string>(cout), "!!");

Using the above line throws this error

/usr/include/c++/5/bits/predefined_ops.h:194:17: error: ISO C++ forbids comparison between pointer and integer [-fpermissive] { return *__it == _M_value; }

Upvotes: 1

Views: 382

Answers (2)

jian
jian

Reputation: 4867

Why you cannot use remove_copy(str.begin(), str.end(),ostream_iterator<string>(cout), "!!"); :

https://www.cplusplus.com/reference/algorithm/remove_copy_if/

pred
Unary function that accepts an element in the range as argument, and returns a value convertible to bool. The value returned indicates whether the element is to be removed from the copy (if true, it is not copied). The function shall not modify its argument. This can either be a function pointer or a function object.

Upvotes: 0

Pdksock
Pdksock

Reputation: 1030

Reading the docs of remove_copy

OutputIterator remove_copy (InputIterator first, InputIterator last,
                          OutputIterator result, const T& val);

The function uses operator== to compare the individual elements to val.

So it uses every character of string and compares it with val. So second case would not work.

I ended up doing it this way

str.erase(str.find("!!"),2);

Also make sure that the string has "!!" otherwise program crashes

if(str.find("!!") != string::npos)
    str.erase(str.find("!!"),2);

Upvotes: 0

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