C program to find array n'th element using pointers

C program to find n'th element in integer array using pointers

This c program is used to get the n'th element in the integer array using pointers and which element is to be read is provided as user input.

Sample code to get nth element using pointers,

Getting first array element,

*ptr

Getting Fifth array element,

*(ptr+4)

Getting seventh array element,

*(ptr+6)

User Inputs:

Reads number of elements in integer array.

Gets array elements

Geths which array element to be read.

Steps:

Prints the array elements with located address

printd nth array element in integer array.

#include<stdio.h>                                                                
                                                                                
void main()                                                                     
{                                                                               
  int i, n, term, *ptr, array[10];                                              
  printf("\nEnter number of elements: ");                                       
  scanf("%d", &n);                                                              
                                                                                
  printf("\nEnter array elements: ");                                           
  for(i=0;i<n;i++)                                                              
  {                                                                             
    scanf("%d", &array[i]);                                                     
  }                                                                             
                                                                                
  printf("\nArray elements with address: ");                                    
  ptr=array; // ptr =&array[0]                                                  
  for(i=0;i<n;i++)                                                              
  {                                                                             
    printf("\nArray[%d] located at address %u: %d", i, *ptr, ptr);              
    ptr++;                                                                      
  }                                                                             
                                                                                
  printf("\nArray element by term: ");                                          
  scanf("%d", &term);                                                           
                                                                                
  ptr=array;                                                                    
  printf("%d term element in array: %d", term, *(ptr+(term-1)));                
                                                                                
}                                                                 
                                                                                  

Output:

$ cc array-nth-element.c
$ ./a.out 

Enter number of elements: 6

Enter array elements: 45
67
87
12
34
52

Array elements with address: 
Array[0] located at address 45: -1246963872
Array[1] located at address 67: -1246963868
Array[2] located at address 87: -1246963864
Array[3] located at address 12: -1246963860
Array[4] located at address 34: -1246963856
Array[5] located at address 52: -1246963852
Array element by term: 4
4 term element in array: 12

When using pointers, garbage value may be displayed for invalid term element in above program because validation is not added.

$ ./a.out 

Enter number of elements: 6

Enter array elements: 34
345
45
57
342
341

Array elements with address: 
Array[0] located at address 34: -2015627296
Array[1] located at address 345: -2015627292
Array[2] located at address 45: -2015627288
Array[3] located at address 57: -2015627284
Array[4] located at address 342: -2015627280
Array[5] located at address 341: -2015627276
Array element by term: 9
9 term element in array: 4196032

Only total elements is 6, so displayed garbage value for 9th term.

Added validation in below for incorrect term element in array,

#include<stdio.h>                                                                
                                                                                
void main()                                                                     
{                                                                               
  int i, n, term, *ptr, array[10];                                              
  printf("\nEnter number of elements: ");                                       
  scanf("%d", &n);                                                              
                                                                                
  printf("\nEnter array elements: ");                                           
  for(i=0;i<n;i++)                                                              
  {                                                                             
    scanf("%d", &array[i]);                                                     
  }                                                                             
                                                                                
  printf("\nArray elements with address: ");                                    
  ptr=array; // ptr =&array[0]                                                  
  for(i=0;i<n;i++)                                                              
  {                                                                             
    printf("\nArray[%d] located at address %u: %d", i, *ptr, ptr);              
    ptr++;                                                                      
  }                                                                             
                                                                                
  printf("\nArray element by term: ");                                          
  scanf("%d", &term); 
  
  if(term <= 0 || term > n)                                                      
  {                                                                             
    printf("\nIncorrect term value!");                                          
    return;                                                                     
  } 
                                                                                
  ptr=array;                                                                    
  printf("%d term element in array: %d", term, *(ptr+(term-1)));                
                                                                                
}                                                                 
                                                                                  

Output:

$ cc array-nth-element.c
$ ./a.out 

Enter number of elements: 5

Enter array elements: 34 
343
45
32
67

Array elements with address: 
Array[0] located at address 34: 1444960848
Array[1] located at address 343: 1444960852
Array[2] located at address 45: 1444960856
Array[3] located at address 32: 1444960860
Array[4] located at address 67: 1444960864
Array element by term: 7

Incorrect term value!