On the basis of a thorough analysis of the methods of declaration and accessing to the static data member in C++ language,authors point out the abuse of utilizing global variable to implement the shared data in program design,and at the same time give out the ways how a static data member replaces the global variable and questions to be paid attention to in using static data member.

The article starts from discussing the concept of global variable in C#,extends to the definition and usage of global used variables with detailed analysis and explanations from different angle and level.

By specially arranging the placement of variables in the stack and accessing the local variables by using as much auto-increment/auto-decrement addressing mode as we can,we can decrease the amount of address arithmatic instruction and promote the program performance.

In advanced language program, the side effect of the subprogram is referred that the subprogram (procedure or function) change public variable or no local variable.