0。 The output formats of printf, int, and longint are all 32 bits, and are output with %d; Both float and double are %f outputs, but float is 32-bit and double is 64-bit. Therefore, when C language passes parameters, it uniformly changes the value of float type to double type and then passes it into printf function, so the integer variable 0.5 outputs 0. Integer variable is a computer language. In C language, the values of integer variables can be decimal, octal and hexadecimal, but binary numbers are stored in memory.