Like any programming language, Solidity provides most of the control and conditional expressions that are provided by Javascript.

It does not have support for switch and goto in if the conditional expression

It provides the following features

  • if-else
  • if-else if

Solidity If the else conditional statement

if-else conditional statements are used to execute statements based on conditional expressions.

Syntax

if (conditional expression){
   //if code block executed 
}
else{
    //else code block executed
}

if condtional expression is true, if code block executed, else else code block executed.

pragma solidity ^0.5.0;

contract SolidityTest {
   uint age; // variable
   constructor() public {
      age = 60;   
   }
   function checkAge() public view returns(string memory) {
      if( age > 60) {   
        return "60";
      } else {
       return "less than 60";
      }       
      return "default"; 
   }
  
}

Output:

0:string: less than 60

Solidity if else if condtional expressions

This is an advanced to basic if-else expression.

It uses to test multiple conditiona if and else expressions.

if (conditional expression1){
   //block 1 executed 
}
else if (conditional expression2){
   //block 2 executed 
}
else{
    //else code block executed
}

conditional expression1 is true, block 1 code executed

conditional expression2 is true, block 2 code executed else block will be executed if both conditions are false.

Here is an example for if-else if conditional expression example

pragma solidity ^0.5.0;

contract SolidityTest {
   uint age; // variable
   constructor() public {
      age = 25;   
   }
   function checkAge() public view returns(string memory) {
      
      if( age < 60) {   
        return "Less than 60";
      
      } else if( age > 60) {   
        return "Greater than 60";
      
      }      
      return "default"; 
   }
  
}
0:string: Less than 60