将字符串初始化为空对空字符串 [英] initializing strings as null vs. empty string
本文介绍了将字符串初始化为空对空字符串的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
如果我的C ++代码(如下所示)有一个初始化为空字符串的字符串,会有什么影响:
How would it matter if my C++ code (as shown below) has a string initialized as an empty string :
std::string myStr = "";
....some code to optionally populate 'myStr'...
if (myStr != "") {
// do something
}
vs。 no / null初始化:
vs. no/null initialization:
std::string myStr;
....some code to optionally populate 'myStr'...
if (myStr != NULL) {
// do something
}
有没有什么最佳实践或困境?
Are there any best practices or gotchas around this?
推荐答案
在 std :: string:
中有一个函数 empty()
/ p>
There's a function empty()
ready for you in std::string:
std::string a;
if(a.empty())
{
//do stuff. You will enter this block if the string is declared like this
}
或
std::string a;
if(!a.empty())
{
//You will not enter this block now
}
a = "42";
if(!a.empty())
{
//And now you will enter this block.
}
这篇关于将字符串初始化为空对空字符串的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文