R Program to Make a Simple Calculator
R Programming Language Decision Making of R Language (Article) Decision Making of R Language (Program)
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In this program we will create a simple calculator using R programming language.
To understand this example, you should have knowledge of following R programming topics:
- R Functions
- R switch()
- R Return Value from Function
Program:
<span class="com"># Program make a simple calculator that can add, subtract, multiply and divide using functions</span><span class="pln"> </span><span class="kwd">add</span><span class="pln"> </span><span class="pun"><-</span><span class="pln"> </span><span class="kwd">function</span><span class="pun">(</span><span class="pln">x</span><span class="pun">,</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> </span><span class="kwd">return</span><span class="pun">(</span><span class="pln">x </span><span class="pun">+</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">}</span><span class="pln"> subtract </span><span class="pun"><-</span><span class="pln"> </span><span class="kwd">function</span><span class="pun">(</span><span class="pln">x</span><span class="pun">,</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> </span><span class="kwd">return</span><span class="pun">(</span><span class="pln">x </span><span class="pun">-</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">}</span><span class="pln"> multiply </span><span class="pun"><-</span><span class="pln"> </span><span class="kwd">function</span><span class="pun">(</span><span class="pln">x</span><span class="pun">,</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> </span><span class="kwd">return</span><span class="pun">(</span><span class="pln">x </span><span class="pun">*</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">}</span><span class="pln"> divide </span><span class="pun"><-</span><span class="pln"> </span><span class="kwd">function</span><span class="pun">(</span><span class="pln">x</span><span class="pun">,</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> </span><span class="kwd">return</span><span class="pun">(</span><span class="pln">x </span><span class="pun">/</span><span class="pln"> y</span><span class="pun">)</span><span class="pln"> </span><span class="pun">}</span><span class="pln"> </span><span class="com"># take input from the user</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="str">"Select operation."</span><span class="pun">)</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="str">"1.Add"</span><span class="pun">)</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="str">"2.Subtract"</span><span class="pun">)</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="str">"3.Multiply"</span><span class="pun">)</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="str">"4.Divide"</span><span class="pun">)</span><span class="pln"> choice </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">as</span><span class="pun">.</span><span class="pln">integer</span><span class="pun">(</span><span class="pln">readline</span><span class="pun">(</span><span class="pln">prompt</span><span class="pun">=</span><span class="str">"Enter choice[1/2/3/4]: "</span><span class="pun">))</span><span class="pln"> num1 </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">as</span><span class="pun">.</span><span class="pln">integer</span><span class="pun">(</span><span class="pln">readline</span><span class="pun">(</span><span class="pln">prompt</span><span class="pun">=</span><span class="str">"Enter first number: "</span><span class="pun">))</span><span class="pln"> num2 </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">as</span><span class="pun">.</span><span class="pln">integer</span><span class="pun">(</span><span class="pln">readline</span><span class="pun">(</span><span class="pln">prompt</span><span class="pun">=</span><span class="str">"Enter second number: "</span><span class="pun">))</span><span class="pln"> </span><span class="kwd">operator</span><span class="pln"> </span><span class="pun"><-</span><span class="pln"> </span><span class="kwd">switch</span><span class="pun">(</span><span class="pln">choice</span><span class="pun">,</span><span class="str">"+"</span><span class="pun">,</span><span class="str">"-"</span><span class="pun">,</span><span class="str">"*"</span><span class="pun">,</span><span class="str">"/"</span><span class="pun">)</span><span class="pln"> result </span><span class="pun"><-</span><span class="pln"> </span><span class="kwd">switch</span><span class="pun">(</span><span class="pln">choice</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">add</span><span class="pun">(</span><span class="pln">num1</span><span class="pun">,</span><span class="pln"> num2</span><span class="pun">),</span><span class="pln"> subtract</span><span class="pun">(</span><span class="pln">num1</span><span class="pun">,</span><span class="pln"> num2</span><span class="pun">),</span><span class="pln"> multiply</span><span class="pun">(</span><span class="pln">num1</span><span class="pun">,</span><span class="pln"> num2</span><span class="pun">),</span><span class="pln"> divide</span><span class="pun">(</span><span class="pln">num1</span><span class="pun">,</span><span class="pln"> num2</span><span class="pun">))</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="pln">paste</span><span class="pun">(</span><span class="pln">num1</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">operator</span><span class="pun">,</span><span class="pln"> num2</span><span class="pun">,</span><span class="pln"> </span><span class="str">"="</span><span class="pun">,</span><span class="pln"> result</span><span class="pun">))</span>
Output:
[1] "Select operation." [1] "1.Add" [1] "2.Subtract" [1] "3.Multiply" [1] "4.Divide" Enter choice[1/2/3/4]: 4 Enter first number: 20 Enter second number: 4 [1] "20 / 4 = 5"
Explanation:
In this program, we ask the user to choose the desired operation. Options 1, 2, 3 and 4 are valid.
Two numbers are taken from the user and a switch branching is used to execute a particular function.
User-defined functions add(), subtract(), multiply() and divide() evaluate respective operations.
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