C++ Program to Show Unreachable Code Error

Unreachable code is code that can never be executed because program control cannot reach it during normal execution.

C++ compilers may detect unreachable code and issue a warning.
Code after an unconditional return statement is a common example of unreachable code.

Example: If a function executes return and then has more statements, those statements cannot be executed because the function has already ended.

return -> Function ends -> Code below return -> Unreachable

Approach

The program follows these steps:

Define a function c() and initialize a variable a with 3.
Return the value of a using the return statement.
Write two more statements after return.
Since return immediately terminates the function, these statements can never be executed.
Call c() from main() and print the returned value.

C++

#include <iostream>
using namespace std;

int c()
{
    int a = 3;

    return a;

    // Unreachable code
    int b = 6;
    cout << b;
}

int main()
{
    cout << c() << endl;

    return 0;
}

Output

Explanation

return a; immediately ends c() and returns 3.
The statements after return can never execute, so they are unreachable code.
main() prints the value returned by c(), resulting in 3.

C++ Program to Show Unreachable Code Error

Approach

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