c++ - 为什么在遍历此 vector 时会出现段错误？

Question

我需要遍历这个 vector 并删除重复项。此代码中某处发生段错误。我的猜测是它与迭代器运行时删除元素有关，但我还没有真正具体了解这些迭代器的实际工作方式，所以我无法弄清楚。

vector<char *>::iterator iter;
for (iter = v->begin(); iter != v->end()-1; iter++ ){
    char *aString = *iter;
    int n = 1;
    while(iter+n != v->end()){
        int comparison = strcmp(aString, *(iter+n));
        if(comparison == 0){
            v->erase(iter + n);
        }
        n++;
    }
}

Answer 1

真的，您这里只是遇到了几个差一的问题。当您删除元素时，您错误地与 end() 进行了比较并递增了 n:

for (iter = v->begin(); iter != v->end()-1; iter++ ){
                                  ^^^^^^^^

和

while(iter+n != v->end())
             ^^

以下将执行您想要的操作(并证明它有效):

int main()
{

    std::vector<const char*> v (4, "this");
    std::vector<const char *>::iterator iter;

    for (iter = v.begin(); iter <  v.end(); iter++ ) {
        std::cout << *iter << " ";
    }
    std::cout << std::endl;

    for (iter = v.begin(); iter <  v.end(); iter++ ){
        const char *aString = *iter;
        int n = 1;
        while(iter+n < v.end()){
            int comparison = strcmp(aString, *(iter+n));
            if(comparison == 0){
                v.erase(iter + n);
            }
            else
                n++;
        }
    }

    for (iter = v.begin(); iter <  v.end(); iter++ ) {
        std::cout << *iter << std::endl;
    }

}

输出是:

this this this this
this