问题描述
我今天在一个程序中遇到了一个有趣的情况，我无意中将一个无符号整数分配给了一个 std::string.VisualStudio C++ 编译器没有给出任何警告或错误，但我在运行项目时碰巧注意到了这个错误，它为我的字符串提供了垃圾字符.
I encountered an interesting situation today in a program where I inadvertantly assigned an unsigned integer to a std::string. The VisualStudio C++ compiler did not give any warnings or errors about it, but I happened to notice the bug when I ran the project and it gave me junk characters for my string.
代码大概是这样的:
std::string my_string("");
unsigned int my_number = 1234;
my_string = my_number;
以下代码也可以很好地编译:
The following code also compiles fine:
std::string my_string("");
unsigned int my_number = 1234;
my_string.operator=(my_number);
以下导致错误:
unsigned int my_number = 1234;
std::string my_string(my_number);
这是怎么回事?为什么编译器会用最后一个代码块停止构建，而让前 2 个代码块构建?
What is going on? How come the compiler will stop the build with the last code block, but let the first 2 code blocks build?
推荐答案
因为 string 可以从 char 赋值，而 int 可以隐式转换为 char.
Because string is assignable from char, and int is implicitly convertible to char.
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