将字符串转换为全部大写 - C++
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Convert String into all uppercase - C++
提问by jordaninternets
I am having trouble turning strings to uppercase for an alphabetical sort. My program actually begins to slow down and freeze after the third set of words. What am I doing wrong?
我无法将字符串转换为大写字母以进行字母排序。在第三组单词之后，我的程序实际上开始变慢和冻结。我究竟做错了什么？
string iName = list[i]->GetLastName(); // This just returns a string of a name
string jName = list[j]->GetLastName();
for(unsigned int k = 0; k < iName.length(); k++)
{
iName[k] = toupper(iName[k]);
}
for(unsigned int l = 0; l < jName.length(); l++)
{
iName[l] = toupper(jName[l]);
}
回答by Hauleth
Use STL algorithmlibrary:
使用 STLalgorithm库：
std::for_each(iName.begin(), iName.end(), std::toupper);
or (suggested by @Kerrek SB)
或（由@Kerrek SB建议）
std::transform(s.begin(), s.end(), s.begin(), std::toupper);
回答by Keith Nicholas
as others said, you mixed iname and jname.... and why did you do this?
正如其他人所说，你混合了 iname 和 jname ......你为什么这样做？
Because you copy pasted!
因为你复制粘贴了！
So, a good early lesson in programming is to try and avoid copy paste! instead try and create functions.....
所以，编程的一个很好的早期教训是尽量避免复制粘贴！而是尝试创建函数.....
in your case...
在你的情况...
void stringToUpper(string &s)
{
for(unsigned int l = 0; l < s.length(); l++)
{
s[l] = toupper(s[l]);
}
}
then you can do
那么你可以做
stringToUpper(iName);
stringToUpper(jName);
This approach redues a LOT of errors related to copy pasting and in general, helps make your programs a lot more modular
这种方法减少了很多与复制粘贴相关的错误，并且通常有助于使您的程序更加模块化
回答by pedorro
The standard suggests that you should not use [] operator on string to modify it's contents. string is designed as an immutable object and your code is breaking that standard. So I guess the answer is that it's hard to say what may be happening because you are using the class in a way in which it was not designed. It could be messing up some internal index or something else. We don't know what the string class may be doing internally.
该标准建议您不应在字符串上使用 [] 运算符来修改其内容。string 被设计为不可变对象，而您的代码正在打破该标准。所以我想答案是很难说可能会发生什么，因为您正在以一种非设计的方式使用该类。它可能会搞乱一些内部索引或其他东西。我们不知道字符串类可能在内部做什么。
That said, it seems like it should work :)
也就是说，它似乎应该工作:)
