Introduction of pointer variables in function parameters

1 Common function encapsulation calls

2 Introduction of pointer variables

1 Common function encapsulation calls ： below Write a piece of code to guess Don't rush to give the answer There will be surprises behind

#include<stdio.h>

// Test whether the size exchange is successful 
void Print(int data,int data2)
{
      int temp;// Swap size 
      temp=data;
      data=data2;
      data2=temp;

}

void  main(void)// Define a  void  Type of   Invisible reference  main  function 
{
    int data=10;//  Define a  int  Type of  data  Variable 
    int data2=11;

    Print( data,data2);// Call the wrapper function 
    printf(" Finally exchange   result  ：%d %d",data,data2);// Print data 


}

This code Not much But it's easy to step into a hole I also believe you have the answer

  Why? There will be such a phenomenon   The function is not called   And print 了  

because c Language Every time you generate a function A memory address will be generated although Assignment occurred however It didn't work

  Because in the main function definition   Just print it out Called function Although the value has passed however Do not operate at the same address   

therefore Can't Link .

The following is the function to be called Introduce change parameter type     That's it Pointer to the variable   Define a pointer variable By assignment Store address to pointer variable   Swap sizes through function operations  

#include<stdio.h>


void Print(int *data,int *data2)
{
      int temp;// Swap size 
      temp=*data;
      *data=*data2;
      *data2=temp;

}

void  main(void)// Define a  void  Type of   Invisible reference  main  function 
{
    int data=10;//  Define a  int  Type of  data  Variable 
    int data2=11;

    Print(&data,&data2);// Call the wrapper function 
    printf(" Finally exchange   result  ：%d %d",*(&data),*(&data2));// Print data 


}

2 Introduction of pointer variables

Let's talk about it first   How does he assign a value when calling a function  

  left arrow   It can be written. int*data=&data Initialization and definition are included here     It's written separately int *data;data=&data; So simple   This is the decomposition of the writing process in which they assign values .

Pointer to the variable Is the variable that stores the address   be relative to Pass the address of a main function To pointer variable ; Inside operation     It's equivalent to the same address     In this way, the number size exchange can be completed .