// erasing from map
#include <iostream>
#include <map>
using namespace std;
int main ()
{
map<char,int> mymap;
map<char,int>::iterator it(mymap.begin());
// insert some values:
mymap['a']=10;
mymap['b']=20;
mymap['c']=30;
mymap['d']=40;
mymap['e']=50;
mymap['f']=60;
it=mymap.find('a');
mymap.erase (it); // erasing by iterator
// show content:
for (; it != mymap.end(); it++ )
cout << (*it).first << " => " << (*it).second << endl;
return 0;
}
为什么这个代码会产生如此输出?a => 10
b => 20
c => 30
d => 40
e => 50
f => 60
为什么"a => 10"
不管怎样都应被删除,但如果我在for循环中声明it = mymap.begin()
,一切就完美了。为什么呢?