a c++ program returns different results in two IDE

The difference appears to be due to whether the floating point operations are using 53-bit precision or 64-bit precision. If you add the following two lines in front of the loop (assuming Intel architecture), it will use 53-bit precision and give the 9220 result when compiled as a 32-bit application:

uint16_t precision = 0x27f;
asm("fldcw %0" : : "m" (*&precision));

It is bits 8 and 9 of the FPU that control this precision. The above sets those two bits to 10. Setting them to 11 results in 64-bit precision. And, just for completeness, if you set the bits to 00 (value 0x7f), the size is printed as 9230.

If I cast both arguments to double I get what you would expect:

pow(static_cast<double>(a), static_cast<double>(b))

You are probably seeing precision errors due to CodeBlocks compiling in 32-bit mode and Eclipse compiling in 64-bit mode:

$ g++ -m32 test.cpp
$ ./a.out
9183
$ g++ -m64 test.cpp
$ ./a.out
9220