Question

How to use const pointers in C

Answer 1

#include <stdio.h>
 
int main(void)
{
    int n;
    const int *p;
    
    p = &n;  
    *p = 23; // error: assignment of read-only location '*p'
 
    return 0;
}
 
   
/*
run:
     
 
*/

 

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Answer 2

#include <stdio.h>
 
int main(void)
{
    int n;
    int *const p = &n; 
    *p = 23;  

    printf("%d", *p);
 
    return 0;
}
 
   
/*
run:
  
23
 
*/

 

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Answer 3

#include <stdio.h>
 
int main(void)
{
    int n;
    int *const p = &n; 
    *p = 23;  

    printf("%d", *p);
   
    int x;
    
    p = &x; // error: assignment of read-only variable 'p'
     
    return 0;
}
 
   
/*
run:
  

 
*/

 

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Answer 4

#include <stdio.h>
 
int main(void)
{
    int n;
    int *const p = &n; 
    
    *p = 23;  
    printf("%d\n", *p);
   
    *p = 100;
    printf("%d\n", *p);
     
    return 0;
}
 
   
/*
run:
  
23
100
 
*/

 

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Answer 5

#include <stdio.h>
 
int main(void)
{
    int n;
    const int* const p = &n;
    
    *p = 23;  // error: assignment of read-only location '*p'

    return 0;
}
 
   
/*
run:
  
23
100
 
*/

 

70+ SQL courses for beginners and professionals