如何在不进行插入的情况下检查 std::map 是否包含键?
我发现检查重复项的唯一方法是插入并检查 std::pair.second
是否为 false
,但问题是这仍然会插入如果密钥未使用,而我想要的是 map.contains(key);
函数.
The only way I have found to check for duplicates is by inserting and checking the std::pair.second
for false
, but the problem is that this still inserts something if the key is unused, whereas what I want is a map.contains(key);
function.
推荐答案
Use my_map.count( key )
;它只能返回0或1,本质上就是你想要的布尔结果.
Use my_map.count( key )
; it can only return 0 or 1, which is essentially the Boolean result you want.
或者 my_map.find( key ) != my_map.end()
也可以.
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