[英]C++ Member Reference base type 'int' is not a structure or union
I'm running into a Problem in my C++ Code. 我在我的C ++代码中遇到了问题。
I have a union StateValue
: 我有一个联合StateValue
:
union StateValue
{
int intValue;
std::string value;
};
and a struct StateItem
和一个结构StateItem
struct StateItem
{
LampState state;
StateValue value;
};
I have a method which goes through a vector of type StateItem
我有一个方法,它通过StateItem
类型的向量
for(int i = 0; i < stateItems.size(); i++)
{
StateItem &st = stateItems[i];
switch (st.state)
{
case Effect:
result += std::string(", \"effect\": ") + st.value.value;
break;
case Hue:
result += std::string(", \"hue\": ") + st.value.intValue.str();
break;
case On:
result += std::string(", \"on\": ") + std::string(st.value.value);
break;
default:
break;
}
}
In the case Hue
I get the following Compiler error: 在Hue
的情况下,我得到以下编译器错误:
Member reference base type 'int' is not a structure or union
I can´t understand the problem here. 我不明白这里的问题。 Can anyone of you please help me? 你能有人帮我吗?
You're trying to call a member function on intValue
, which has type int
. 您正在尝试在intValue
上调用成员函数,其类型为int
。 int
isn't a class type, so has no member functions. int
不是类类型,因此没有成员函数。
In C++11 or later, there's a handy std::to_string
function to convert int
and other built-in types to std::string
: 在C ++ 11或更高版本中,有一个方便的std::to_string
函数将int
和其他内置类型转换为std::string
:
result += ", \"hue\": " + std::to_string(st.value.intValue);
Historically, you'd have to mess around with string streams: 从历史上看,你不得不乱用字符串流:
{
std::stringstream ss;
ss << st.value.intValue;
result += ", \"hue\": " + ss.str();
}
Member reference base type 'int' is not a structure or union
int
is a primitive type, it has no methods nor properties. int
是基本类型,它没有方法也没有属性。
You are invoking str()
on a member variable of type int
and that's what the compiler is complaining about. 您正在对int
类型的成员变量调用str()
,这是编译器抱怨的内容。
Integers cannot be implicitly converted to string, but you can used std::to_string()
in C++11, lexical_cast
from boost
, or the old-slow approach of the stringstream
. 整数不能隐式转换为字符串,但你可以在C ++ 11中使用std::to_string()
,使用boost
lexical_cast
,或者使用stringstream
的旧 - 慢速方法。
std::string to_string(int i) {
std::stringstream ss;
ss << i;
return ss.str();
}
or 要么
template <
typename T
> std::string to_string_T(T val, const char *fmt ) {
char buff[20]; // enough for int and int64
int len = snprintf(buff, sizeof(buff), fmt, val);
return std::string(buff, len);
}
static inline std::string to_string(int val) {
return to_string_T(val, "%d");
}
And change the line to: 并将行更改为:
result += std::string(", \"hue\": ") + to_string(st.value.intValue);
Your intvalue is no object. 你的intvalue不是对象。 It has no member functions. 它没有成员功能。 You could use sprintf() or itoa() to convert it to a string. 您可以使用sprintf()或itoa()将其转换为字符串。
intValue
是一个int
,它没有方法。
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