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a trap of string.html
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a trap of string.html
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<title>a trap of string</title>
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<div class="inner">
<h1>Wiki</h1>
<h2>by chenokay</h2>
<a href="https://github.com/chenokay" class="button"><small>View my project on</small>GitHub</a>
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<h1 id="toc_1">A trap of string</h1>
<pre>
#include <stdio.h>
#include <string>
enum T {
ELE1 = 0,
ELE2
};
int main()
{
std::string a;
a = ELE1;
std::string b = "hello";
b.append(a);
b.append("world");
printf("pint:%s\n", b.c_str());
return 0;
}
</pre>
<p>
这段代码会输出多少呢？
</p>
<p>
"helloworld" ?
</p>
<p>
不是的，实际的结果是hello，因为在a的初始化赋值中，ELE1被当做char类型进行构造，得到一个
</p>
<p>
长度为1，值为0的string，导致在a append到b后，再append的内容都被a的0字符截断而
</p>
<p>
没有打印出来。
</p>
<p>
实际上，在append操作中，是根据length长度来进行的，只要生成一个包括'\0'的string进行append
</p>
<p>
都会导致后续的append不能打印。
</p>
<p>
当然，若string a = "\0"; 是没有问题的，所以要分清string中'\0'字符和字符串的结尾'\0';
</p>
<p>
稍大意就造成问题。
</p>
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<aside id="sidebar">
<h2>Zhen Chen</h2>
<p><a href="http://map.baidu.com/?newmap=1&ie=utf-8&s=s%26wd%3D%E5%A4%9A%E7%9B%9F">No.15 Wanquanzhuang Road, Haidian District, Beijing, China</a></p>
<p>chenokay@gmail.com</p>
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