[Error] narrowing conversion of '20' from 'int' to 'bool' [-Wnarrowing]
时间: 2024-01-20 17:03:02 浏览: 46
这个错误是因为你试图将一个整数值转换为布尔类型,但是这个整数值并不是0或1,因此会出现缩小转换的错误。
在 C++ 中,bool 类型只能取 true 或 false 两个值,即 1 或 0。如果你需要将一个整数转换为布尔类型,你可以使用条件运算符来实现。例如,以下代码将整数 x 转换为布尔类型:
```cpp
bool b = (x != 0) ? true : false;
```
这里使用了条件运算符 ? :,如果 x 不为 0,则 b 的值为 true,否则为 false。
相关问题
error: narrowing conversion of ‘170’ from ‘int’ to ‘char’ inside
这个错误是由于将一个整数类型的值强制转换为 char 类型时,超出了 char 类型的取值范围所导致的。在 ASCII 码表中,char 类型的取值范围是 0~127,因此当你尝试将一个大于 127 的整数强制转换为 char 类型时,就会出现 narrowing conversion 的错误。要解决这个问题,可以将整数类型改为与 char 类型相同的类型。或者,如果你确定要将这个整数值转换为 char 类型,可以使用 static_cast 进行强制转换,并在转换前确保它不超出 char 类型的取值范围。
Clang-Tidy: Narrowing conversion from 'double' to 'int'
This warning message from Clang-Tidy indicates that there is a potential narrowing conversion from a double type to an int type. A narrowing conversion means that some information might be lost during the conversion.
In C++, a double is a floating-point type that can represent decimal numbers with a higher precision compared to an int, which is an integer type. When you assign a double value to an int variable, the compiler may issue a warning because the fractional part of the double value will be truncated, losing precision.
To resolve this warning, you have a few options:
1. If you are intentionally truncating the fractional part, you can use a static_cast to explicitly convert the double value to an int:
```cpp
double myDouble = 3.14;
int myInt = static_cast<int>(myDouble);
```
2. If you want to perform a rounding operation, you can use the round or nearbyint functions from the `<cmath>` library:
```cpp
#include <cmath>
double myDouble = 3.14;
int myInt = std::round(myDouble); // or std::nearbyint(myDouble)
```
3. If you want to avoid the narrowing conversion altogether, you can choose a different type that can represent decimal numbers with higher precision, such as float or double.
It's important to note that the appropriate solution depends on your specific use case and the desired behavior of your program.