Question

How to use const pointer in C

Answer 1

#include <stdio.h>

int main() {
    int n = 20;
    const int *p1 = &n;
    printf("a. %d %d\n", n, *p1);
    n = 900;
    // *p = 800; // error: assignment of read-only variable ‘p1’
    printf("b. %d %d\n", n, *p1);
 
    int x = 50;
    p1 = &x;
    printf("c. %d %d %d\n", n, *p1, x);
    
    n = 1000;    
    int * const p2 = &n;
    printf("d. %d %d\n", n, *p2);
    // p2 = &x; // error: assignment of read-only variable ‘p2’
    *p2 = 17;
    printf("e. %d %d\n", n, *p2);

    return 0;
}
 


/*
run:
 
a. 20 20
b. 900 900
c. 900 50 50
d. 1000 1000
e. 17 17
 
*/

 

70+ SQL courses for beginners and professionals