'operator' : no conversion from 'type1' to 'type2'
The compiler is unable to convert type1 to type2. Normally the compiler is able to convert from one type to another, but sometimes a conversion does not make sense because it would violate the semantics of C or C++. If you’ve encountered this error on code which compiled with an earlier version of Visual C++, please read Technote: Improved Conformance to ANSI C++ for more information.
The example below illustrates two conversion problems:
int i;
char *p;
int *j;
const int *cj;
void main()
{
p = i; // ERROR #1: conversion has no meaning
j = cj; // ERROR #2: pointer to const obj
}