C language learning Notes (2)

I. pointer array

1. The array of function parameters of the table pointer is actually

sizeof(a) == sizeof(int * );
int a[ ] ⇔ int *a
The following four function prototype is equivalent to:

• you sum (you ar *, you're n);
• you sum (you ar [], you're n);
• int sum (int *, int);
• int sum (int[ ],int);
  
  

2. The array variable is a special pointer

• Array itself indicates the address,
  • int a[10];
  • int * p = a; // no need to take a variable &
    
• Expression of cell array is a variable, & need to take address.
• [] Operator can make the array, a pointer can be done;
  P [0] ⇔ A [0]

• * Operator can use the pointer, the array can be made;

• Const array variable is a pointer type, and therefore can not be changed assignment;
  int A [] ⇔ const int * B;
  
  

  II. Pointer arithmetic

  (1) to add a pointer, a subtraction integer (+, + =, -, - =);
  (2) increment decrement (+, -);
  (3) subtracting two pointers;

1. Modified:

• I.e., plus a pointer to the address indicated by the pointer value plus a sizeof (pointer type), move to the next cell.
• Pointer 1 - direction of the cell 2 is the difference between the result of, not the value of the address difference between:
  (Pointer 1-- Pointer 2) / sizeof (pointer type);

2. *p++

• After removing the data referred to p, p is moved to the next cell;
• An array of space-based continuous operation;
• In some CPU, which can be directly translated into an assembler instruction;

3. Compare pointer

• ! <, <=, ==,>,> =, = pointer may be compared (compare memory address);
• Address of the array increases linearly.

4.0 Address

• A 0 address is typically not able to touch the random address;
• Pointer should not have a value of 0;
• Usually expressed special things with 0 Address:
  • Return an invalid value;
  • Pointer is not actually initialized.
• NULL is a predefined symbols, represents the address 0

The pointer type

• No matter what type of points, the size of all the pointers are the same, because all addresses;
• Pointers point to different types of assignment is not directly to each other; this is to avoid using the wrong hands.

6. The pointer action

• When passed as an argument requires large transactions;
• After passing an array of arrays to do the operation;
• Function returns more than one result;
• Need to modify more than one variable function;
• Dynamic application memory.

My handwritten notes

MOOC Code

Issues arising

1. * p ++ meaning

Resolution: The unary * + and below the level of the value P taken out after the P position to the next.