j*****k
发帖数: 1198 | 1 想用stl sort来按string size排序。在relational function cmp里面
如果这样用就没问题
bool cmp(string &s1, string &s2)
{
return s1<=s2;
}
可是如果以下面的方式用，就会出现segment fault, 什么原因呢？
bool cmp(string &s1, string &s2)
{
return (s1.length()) <= (s2.length());
}
谢谢 | s***e
发帖数: 793 | 2 i do not know where the problem is
but it is more robust to write the cmp this way
bool cmp(const string & s1, const string s2){
return (s1.length())<(s2.length()); // prefer < over <=
}
【在 j*****k 的大作中提到】
: 想用stl sort来按string size排序。在relational function cmp里面
: 如果这样用就没问题
: bool cmp(string &s1, string &s2)
: {
: return s1<=s2;
: }
: 可是如果以下面的方式用，就会出现segment fault, 什么原因呢？
: bool cmp(string &s1, string &s2)
: {
: return (s1.length()) <= (s2.length());
| j*****k
发帖数: 1198 | 3 能请教一下，为什么不能用<=么
【在 s***e 的大作中提到】
: i do not know where the problem is
: but it is more robust to write the cmp this way
: bool cmp(const string & s1, const string s2){
: return (s1.length())<(s2.length()); // prefer < over <=
: }
:
| p***o
发帖数: 1252 | 4 It is required by the algorithm. Read 25.3 of the C++ standard.
3 For all algorithms that take Compare, there is a version that uses
operator< instead. That is, comp(*i, *j) != false defaults to
*i < *j != false. For the algorithms to work correctly, comp has
to induce a strict weak ordering on the values.
4 The term strict refers to the requirement of an irreflexive relation
(!comp(x, x) for all x), and the term weak to requirements that are
not as strong as those for a total ordering
【在 j*****k 的大作中提到】
: 能请教一下，为什么不能用<=么
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