std::remove does not work

Question

The goal of my test program is to erase a cell in a simple vector of strings like below. The program fail (segmentation fault).

static void display(std::vector<std::string> const &vec)
{
    std::vector<std::string>::const_iterator It = vec.begin();
    for (; It != vec.end(); ++It)
        std::cout << *It << " ";
    std::cout << std::endl;
}


int         main(void)
{
    std::vector<std::string> vec;
    size_t  index = 0;

    vec.push_back("Toto");
    vec.push_back("Titi");
    vec.push_back("Tata");
    vec.push_back("Tutu");

    display(vec);

    std::vector<std::string>::iterator It = vec.begin();

    for (size_t idx = 0; It != vec.end(); ++It, idx++)
        if (!(*It).compare("Tutu"))
            index = idx;

    vec.erase(std::remove(vec.begin(), vec.end(), index), vec.end()); //Segmentation fault

    display(vec);

    getchar();
    return (0);
}

Does anyone can help me? Thanks in advance for your help.

Read about the arguments to `remove` more carefully. It does not take an index. — Pete Becker, Dec 01 '12 at 16:38

score 5 · Accepted Answer · answered Dec 01 '12 at 16:38

5

vec.erase(std::remove(vec.begin(), vec.end(), index), vec.end());

You need to pass the actual element (in this case of type std::string) to your erase function.

So instead of index, it should be somestring

answered Dec 01 '12 at 16:38

Tony The Lion

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I'm confused, why do you need to use erase aswell as remove? cppreference.com says: 1) Removes all elements that are equal to value. https://en.cppreference.com/w/cpp/algorithm/remove – Iron Attorney Jul 17 '18 at 10:05

score 0 · Answer 2 · answered Dec 01 '12 at 17:40

you shall not mix iterators and homebrew indices. use the iterators only.
algorithms like copy - there are external algorithms for use when you want to decouple from the actual container type and there are member functions that do an optimized job. in your case vec erase does everhting for you, just pass the found iterator

vec.erase(It);

score 0 · Answer 3 · answered Dec 01 '12 at 18:21

Since you're checking for equality, just use std::remove:

vec.erase( std::remove( vec.begin(), vec.end(), "Tutu" ),
           vec.end() );

It's the standard idiom. If for some reason, you have to write the loop yourself:

std::vector<std::string>::const_iterator current = vec.begin();
while ( current != vec.end() ) {
    if ( *current == "Tutu" ) {
        current = vec.erase( current ) ;
    } else {
        ++ current;
    }
}

(Again, the standard idiom.)

std::remove does not work

3 Answers3

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