Compiler Warning (level 4) C4245
Collapse the table of content
Expand the table of content
Important This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here. ArchiveDisclaimer

Compiler Warning (level 4) C4245

Error Message

'conversion' : conversion from 'type1' to 'type2', signed/unsigned mismatch

You tried to convert a signed const that has a negative value to an unsigned.

The following sample generates C4245:

// C4245.cpp
// compile with: /W4 /c
const int i = -1;
unsigned int j = i; // C4245

const int k = 1;
unsigned int l = k; // okay

int m = -1;
unsigned int n = m; // okay

void Test(size_t i) {}

int main() {
   Test( -19 );   // C4245
© 2016 Microsoft