"C Language" "C programming language" read through extracts

• The precedence of the not equal to operator! = is higher than the precedence of the assignment operator =;

• The parameter value passed to the called function is stored in a temporary variable, not in the original variable, so the called function cannot directly modify the value of the variable in the key function, but only the value of its private temporary copy;

• Each local variable in the function is only present when the function is called and disappears when the function is finished.

• The function can exchange data through an external variable without having to use the parameter table;

• The declaration of any variable can be qualified with the Const qualifier, and the value of the qualifier-setting variable cannot be modified;

• The modulo operator% cannot be applied to a float or double type;

• Normally, the function name is globally accessible and visible to all parts of the program. However, if the function is declared as a static type, the function name cannot be accessed except for the file where the function declaration is located;

• Register declaration is only applicable to automatic variables and formal parameters of functions;

• In fact, the register variable is not necessarily saved in the Register, but its address is inaccessible regardless of whether the register variable is actually stored in the register.

• In the absence of explicit initialization, both the external and static variables are initialized to 0, and the initial values of the automatic and register variables are undefined;

• For external variables and static variables, the initialization expression must be a constant expression and be initialized only once. For the automatic variable and register variable, it will be initialized each time the function or block is entered;

• A pointer is a variable that holds the address of a variable;

• The address operator & can only be applied to objects in memory, that is, variables and array elements. It cannot act on an expression, a constant, or a variable of the register type;

• Pointer parameters enable the called function to access and modify the value of the object in the key function;

"C Language" "C programming language" read through extracts