Compiler Warning (level 4) C4709


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The latest version of this topic can be found at Compiler Warning (level 4) C4709.

comma operator within array index expression

When a comma occurs in an array index expression, the compiler uses the value after the last comma.

The following sample generates C4709:

// C4709.cpp  
// compile with: /W4  
#include <stdio.h>  
int main()   
    int arr[2][2];  
    arr[0][0] = 10;  
    arr[0][1] = 11;  
    // Prints 10, not 11  
    printf_s("\n%d",arr[0][1,0]);   // C4709