Program to calculate the sum of first n natural numbers using while loop

C Programming Language Loop control in C Language (Article) Loop control in C Language (Program)

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Program:

<span class="com">// Program to calculate the sum of first n natural numbers</span><span class="pln">
</span><span class="com">// Positive integers 1,2,3...n are known as natural numbers</span><span class="pln">

</span><span class="com">#include</span><span class="pln"> </span><span class="str">&lt;stdio.h&gt;</span><span class="pln">
</span><span class="kwd">int</span><span class="pln"> main</span><span class="pun">()</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
    </span><span class="kwd">int</span><span class="pln"> num</span><span class="pun">,</span><span class="pln"> count</span><span class="pun">,</span><span class="pln"> sum </span><span class="pun">=</span><span class="pln"> </span><span class="lit">0</span><span class="pun">;</span><span class="pln">

    printf</span><span class="pun">(</span><span class="str">"Enter a positive integer: "</span><span class="pun">);</span><span class="pln">
    scanf</span><span class="pun">(</span><span class="str">"%d"</span><span class="pun">,</span><span class="pln"> </span><span class="pun">&amp;</span><span class="pln">num</span><span class="pun">);</span><span class="pln">
    
      count </span><span class="pun">=</span><span class="pln"> </span><span class="lit">1</span><span class="pun">;</span><span class="pln"> 
     
    </span><span class="kwd">while</span><span class="pun">(</span><span class="pln">count </span><span class="pun">&lt;=</span><span class="pln"> num</span><span class="pun">)</span><span class="pln">
    </span><span class="pun">{</span><span class="pln">
        sum </span><span class="pun">+=</span><span class="pln"> count</span><span class="pun">;</span><span class="pln">
        </span><span class="pun">++</span><span class="pln">count</span><span class="pun">;</span><span class="pln">
    </span><span class="pun">}</span><span class="pln">

    printf</span><span class="pun">(</span><span class="str">"Sum = %d \n"</span><span class="pun">,</span><span class="pln"> sum</span><span class="pun">);</span><span class="pln">

    </span><span class="kwd">return</span><span class="pln"> </span><span class="lit">0</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span>

Output:

Enter a positive integer: 10
Sum = 55
Press any key to continue . . .

Explanation:

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