function declaration vs function definition code example

Example 1: declaration vs. definition cpp

\\this is the declaration
int declaration();

\\this is the definition
int definition = 0

Example 2: function expression vs function declaration

const functionExpression = function(width, height) {
  return width * height;
};

console.log(functionExpression(3, 4));
// Result = 12

function functionDeclaration(width,height){
return width * height;
};

console.log(functionDeclaration(3,4));
//Result = 12