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Compiler Warning (level 1) C4305

  • Artikkeli

'conversion': truncation from 'type1' to 'type2'

Remarks

This warning is issued when a value is converted to a smaller type in an initialization or as a constructor argument, resulting in a loss of information.

Example

This sample shows two ways you might see this warning:

// C4305.cpp
// Compile by using: cl /EHsc /W4 C4305.cpp

struct item
{
    item(float) {}
};

int main()
{
    float f = 2.71828;          // C4305 'initializing'
    item i(3.14159);            // C4305 'argument'
    return static_cast<int>(f);
}

To fix this issue, initialize by using a value of the correct type, or use an explicit cast to the correct type. For example, use a float literal such as 2.71828f instead of a double (the default type for floating-point literals) to initialize a float variable, or to pass to a constructor that takes a float argument.