Using pointer arithmetic to calculate sum of array in C

In this program, we need to use pointer arithmetic to find the sum of array elements.

Here we use * to represent the value stored at the memory address, and the address will remain stored in the variable. So "int *ptr" means that ptr is a variable containing an address whose content is an integer.

*p means it is a pointer variable. Using this and sum() we will find the sum of the array elements.

Sample code

<span class="com">#include</span><span class="pln"> </span><span class="str"><stdio.h></span>
<span class="kwd">void</span><span class="pln"> s</span><span class="pun">(</span><span class="kwd">int</span><span class="pun">*</span><span class="pln"> a</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">int</span><span class="pln"> len</span><span class="pun">) </span><span class="pun">{</span>
<span class="kwd">   int</span><span class="pln"> i</span><span class="pun">,</span><span class="pln"> s_of_arr </span><span class="pun">=</span><span class="pln"> </span><span class="lit">0</span><span class="pun">;</span>
<span class="kwd">   for</span><span class="pln"> </span><span class="pun">(</span><span class="pln">i </span><span class="pun">=</span><span class="pln"> </span><span class="lit">0</span><span class="pun">;</span><span class="pln"> i </span><span class="pun"><</span><span class="pln"> len</span><span class="pun">;</span><span class="pln"> i</span><span class="pun">++)</span>
<span class="pln">      s_of_arr </span><span class="pun">=</span><span class="pln"> s_of_arr </span><span class="pun">+</span><span class="pln"> </span><span class="pun">*(</span><span class="pln">a </span><span class="pun">+</span><span class="pln"> i</span><span class="pun">);</span>
<span class="pln">   printf</span><span class="pun">(</span><span class="pln"> </span><span class="str">"sum of array is = %d"</span><span class="pln"> </span><span class="pun">,</span><span class="pln">s_of_arr</span><span class="pun">);</span>
<span class="pun">}</span>
<span class="kwd">int</span><span class="pln"> main</span><span class="pun">() </span><span class="pun">{</span>
<span class="kwd">   int</span><span class="pln"> arr</span><span class="pun">[]</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> </span><span class="lit">1</span><span class="pun">,</span><span class="lit">2</span><span class="pun">,</span><span class="lit">4</span><span class="pun">,</span><span class="lit">6</span><span class="pun">,</span><span class="lit">7</span><span class="pun">,-</span><span class="lit">5</span><span class="pun">,-</span><span class="lit">3</span><span class="pln"> </span><span class="pun">};</span>
<span class="pln">   s</span><span class="pun">(</span><span class="pln">arr</span><span class="pun">,</span><span class="pln"> </span><span class="lit">7</span><span class="pun">);</span>
<span class="kwd">   return</span><span class="pln"> </span><span class="lit">0</span><span class="pun">;</span>
<span class="pun">}</span>

Output

Sum of array = 12

Algorithm

Begin
   Initialize array to hold the variables.
   Call function s to get the sum of the variables.
   Print the sum.
End.

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