In C language, integer operation and real number operation are two different operations, which are different from mathematics.

For example:

int a= 1，b = 2；

A/b=0, not 0.5.

Floating point numbers a= 1, b = 2；;

a/b=0.5

Therefore, in the mixed operation of integer and real number types, the integer type should be converted into real number type before the operation.