Update control-flow--statements@s5Gs4yF9TPh-psYmtPzks.md

Added brief intro about C++ control statements.

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-# Control Flow & Statements
+# Control Flow & Statements
+Control flow & statements provides the ability to make decision which part of code should be executed or not based on certain conditions(also called decision control statements). In C++, the different types of control statements are:
+  
+  ## 1. if
+  Simplest way to check weather a conditon is true or false and make a decision.
+  
+```cpp
+  //Syntax
+  
+  if(condition_to_be_evaluated){
+  //code to be executed when condition evaluates to true.
+  // this section will only execute if specified condition is
+  // met. Else it won't.
+  }
+
+```
+  ```cpp
+     int age = 19;
+     // check if age is greater than 19.
+     if(age > 18) {
+      std::cout << "You are eligible to vote" << std::endl;
+     }
+
+```
+Note: You can skip to write curly brasses if there is only one statement.
+```cpp
+    int age = 19;
+    if (age > 18)
+        cout << "allowed to vote";
+    return 0;
+```
+
+ ## 2. if else:
+ When if condition is not evualuated true and you still want to execute some code, then if-else is used.
+ ```cpp
+  //Syntax
+  
+  if(condition_to_be_evaluated){
+  //code to be executed when condition evaluates to true.
+  // this section will only execute if specified condition is
+  // met. Else it won't.
+  } else {
+  // code to be excuted only when if does not
+  // match to specified condition.
+}
+
+```
+ ```cpp
+     int age = 10;
+     // check if age is greater than 19.
+     if(age > 18) {
+      std::cout << "You are eligible to vote" << std::endl;
+     } else {
+    std::cout << "Not eligible to vote" << std::endl;
+  }
+```
+ 
+  ## 3. Switch:
+     
+```cpp
+  //Syntax
+  
+  switch(expression_to_be_compared){
+    case 'Value_A':
+    std::cout << "Value is A" <<std::endl;
+    break;
+    case 'Value_B':
+    std::cout << "Value is B" <<std::endl;
+    break;
+
+    default:
+    // to be excuted when no case is matched.
+    std::cout << "No match or invalid expression" <<std::endl;
+    break;
+    // NOTE: break keyword is used so that program execution is stopped weather a case
+    //matches or not.
+  }
+
+```
+## 4. Ternary Operator: 
+ Ternary operator also known as conditonal operator is used to write conditonal operations in C++.
+ The '?' operator checks the given condition, if true then first expression is executed before  ':' otherwise second expression is executed after ':'.
+Similar to if else but one liner.
+
+```cpp
+int a = 1, b = 2;
+int ans;
+
+max = (a > b) ? a : b;
+std::cout << max;
+```
+
+To read more in depth about control statements such as if else if ladder , Nested if, Jump, goto, break. Check this out: https://www.geeksforgeeks.org/cpp-decision-making/