Why is onlineGDB not giving the same result as another compiler?

Why is onlineGDB not giving the same result as another compiler? onlinegdb OnlineGDB is described as 'Com is an online compiler and debugger tool for CC++ Code, compile and run program in browser and debug program onlinegdb OnlineGDB is a web-based IDE that offers an intuitive interface for writing code in various programming languages such as C, C++, Java, Python,

onlinegdb OnlineGDB is online IDE with C++ compiler Quick and easy way to compiler c++ program online It supports g++ compiler for c++

onlinegdb OnlineGDB is online IDE with java compiler Learn more about IntelliJ IDEA's features, compare it with other JetBrains products, and discover how it can OnlineGDB is described as 'Com is an online compiler and debugger tool for CC++ Code, compile and run program in browser and debug program