Skip to main content

How to declare pointers in c?

Below is the general form of pointer declaration.

datatype  * var_name;

datatype   - type of data to which the pointer points to
 *             - indirection operator(used to represent pointer)
var_name - name of the pointer variable.

The following are few pointer declarations:
char  * char_ptr;  /* pointer to character */
int     *integer_ptr; /* pointer to integer */
float  *float_ptr;  /* pointer to float */

How to assign values to pointers in c?
Below program illustrates how to assign values to pointers.


  #include <stdio.h>
  #include <string.h>

  int main() {
        char *char_ptr, str[32];
        int *int_ptr, int_val;
        float *float_ptr, float_val;

        /* assigning values to non-pointer variables */
        strcpy(str, "String");
        int_val = 100;
        float_val = 98.9;

        /* 
         * address of non-pointer variables 
         * is assigned as value for pointers
         */
        char_ptr = &str[0];
        int_ptr = &int_val;
        float_ptr = &float_val;

        /* printing the address of variables and values of pointers */
        printf("Value of int_ptr: 0x%x\tAddress of "
                "int_val: 0x%x\n", (int)int_ptr, (int)&int_val);
        printf("Value of char_ptr: 0x%x\tAddress of "
                "str[0]: 0x%x\n", (int)char_ptr, (int)&str[0]);
        printf("Value of float_ptr: 0x%x\tAddress of "
                "float_val: 0x%x\n", (int)float_ptr, (int)&float_val);

        /* printing the values pointed by pointer */
        printf("\n*int_ptr: %d\n", *int_ptr);
        printf("*float_ptr: %.2f\n", *float_ptr);
        printf("string pointed by char_ptr: ");
        while (*char_ptr != '\0') {
                printf("%c", *char_ptr);
                char_ptr++;
        }
        printf("\n");

        return 0;
  }




  Output:
  jp@jp-VirtualBox:~/$ ./a.out
  Value of int_ptr: 0xbf9da510 Address of int_val: 0xbf9da510
  Value of char_ptr: 0xbf9da51c Address of str[0]: 0xbf9da51c
  Value of float_ptr: 0xbf9da508 Address of float_val: 0xbf9da508

  *int_ptr: 100
  *float_ptr: 98.90
  string pointed by char_ptr: String


Labels:

Comments

Post a Comment

Popular posts from this blog

Array of pointer to structure

Array of pointer to structure is nothing but an array whose elements are pointers to structure How to declare array of pointer to structure? Below is an example declaration for array of pointer to structure. struct student *arr[10]; Here, arr is an array 10 of pointer to structure student. Dynamic memory allocation: Below is the procedure to perform dynamic memory allocation for the structure pointers in an array. struct student { int age; char name[32]; }; fun() { int i = 0; struct student *arr[10]; for (i = 0; i < 10; i++) { /* dynamic memory allocation for 5 structure objects */ arr[i] = (struct student *)malloc(sizeof(struct student) * 5); } } Write a c program to pass an array of structure pointers to another function   #include <stdio.h>   #include <stdlib.h>   #include <string.h>   struct student {         int age, rollno;         char name[32];   };   /* printing details of stude...
Post a Comment
Read more

Nested function in C

What is nested function? If a function is defined inside another function, then it is called as nested function.  Nested function example in C: Consider the following example, int add(int a, int b) {        void print(int res) {          printf("Result is %d, res);       }       print(a+b);       return 0; } Here, print() is a nested function.  Because, it is defined inside another function named add() . Example C program using nested functions: #include <stdio.h> void add(int a, int b) { void print(int res) { // nested function printf("Result is %d\n", res); return; } print(a + b); // passing sum of a and b as parameter return; } int main() { add(10, 20); return 0; }   Output:   jp@jp-VirtualBox:~/$ ./a.out   Result is 30 Previous Next
Post a Comment
Read more

Difference between asterisk and ampersand operators in c

Address Operator (& - Ampersand): Returns address of the given variable.  Consider the following example, int *ptr, var = 10; ptr = &var; ptr = &var sets the address of the variable var to pointer ptr.  & is also called as reference operator. Let us try to understand the purpose of reference operator using the following example program.   #include <stdio.h>   int main() {         int var = 10, *ptr;         /* assigning address of variable var to pointer ptr */         ptr = &var;         /* printing the address of the variable var */         printf("Address of var is 0x%x\n", &var);         /* printing the value of pointer ptr */         printf("Value of ptr is 0x%x\n", ptr);         return 0;   }   Output:   jp@jp-VirtualBox:~/$ ./a.out   Address of var is 0x...
Post a Comment
Read more