在字符串 C++ 中查找字符位置
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Find a character position in a string C++
提问by user3395662
How can I find the position of a character in a string? Ex. If I input "abc*ab" I would like to create a new string with just "abc". Can you help me with my problem?
如何在字符串中找到字符的位置？前任。如果我输入“abc*ab”，我想用“abc”创建一个新字符串。你能帮我解决我的问题吗？
回答by
std::findreturns an iterator to the first element it finds that compares equal to what you're looking for (or the second argument if it doesn't find anything, in this case the end iterator.) You can construct a std::stringusing iterators.
std::find将迭代器返回到它找到的第一个元素，该元素与您要查找的元素相比较（如果没有找到任何内容，则返回第二个参数，在本例中为结束迭代器。）您可以std::string使用迭代器构造一个迭代器。
#include <iostream>
#include <string>
#include <algorithm>
int main()
{
std::string s = "abc*ab";
std::string s2(s.begin(), std::find(s.begin(), s.end(), '*'));
std::cout << s2;
return 0;
}
回答by 6502
C++ standard string provides a findmethod:
C++标准字符串提供了一种find方法：
s.find(c)
returns the position of first instance of character cinto string sor std::string::nposin case the character is not present at all. You can also pass the starting index for the search; i.e.
将字符的第一个实例的位置返回c到字符串中，s或者std::string::npos在字符根本不存在的情况下。您还可以传递搜索的起始索引；IE
s.find(c, x0)
will return the first index of character cbut starting the search from position x0.
将返回字符的第一个索引，c但从 position 开始搜索x0。
回答by Victor
If you are working with std::stringtype, then it is very easy to find the position of a character, by using std::findalgorithm like so:
如果您正在使用std::string类型，那么通过使用如下std::find算法很容易找到字符的位置：
#include <string>
#include <algorithm>
#include <iostream>
using namespace std;
int main()
{
string first_string = "abc*ab";
string truncated_string = string( first_string.cbegin(), find( first_string.cbegin(), first_string.cend(), '*' ) );
cout << truncated_string << endl;
}
Note:if your character is found multiple times in your std::string, then the findalgorithm will return the position of the occurrence.
注意：如果你的角色在你的 中多次找到std::string，那么find算法将返回出现的位置。
