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C6293

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Note

This article applies to Visual Studio 2015. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here

warning C6293: Ill-defined for-loop: counts down from minimum

This warning indicates that a for-loop might not function as intended. It occurs when a loop counts down from a minimum, but has a higher termination condition.

A signed —or unsigned—index variable together with a negative increment will cause the loop to count negative until an overflow occurs. This will terminate the loop.

Example

The following sample code generates this warning:

void f( )  
{  
   signed char i;  
  
   for (i = 0; i < 100; i--)  
   {  
      // code ...  
   }  
}

To correct this warning, use the following code:

void f( )  
{  
   signed char i;  
  
   for (i = 0; i < 100; i++)  
   {  
      // code ...  
   }  
}