1. First of all, a mind map of the elementary C language, from which you can understand a general framework of the C language.
2. Then there are some notes to share:
The life cycle of local variables is: enter the scope life cycle start;
The life cycle of global variables is: the life cycle of the entire program;
The scope of a local variable is: the local scope where the local variable is located;
The scope of global variables is: the entire project.
For division, if there are integers on both sides of /, integer division is performed, and decimal division is performed as long as there is a decimal at both ends.
% Modulo operator, the left and right operands must be integers, not decimals.
Front ++, formula: first +1, then use;
Rear ++, formula: use first, then +1;
Front and rear - the same is true.
The dangling else matches the nearest and unmatched if, which is a bad code style.
When static modifies the global variable, the scope of the variable is changed so that it can only be used in the source file where it is located;
When modifying local variables, the life cycle is changed, and the life cycle becomes longer;
Modified function, changing the connection attribute of the function; (roughly speaking, changing the scope)
As the name implies, typedef is a type definition, which should be understood as type renaming here.
The pointer size is 4 bytes on 32 -bit platforms and 8 bytes on 64 -bit platforms .
Each element of the array has a subscript, and the subscript starts from 0 .