#include <iostream>

// The following program does not compile.
//
// Identify why it does not compile, and then fix
// the problem so that the program prints the
// absolute value of the integer entered by the user.
//
// Try to find the bug before compiling the program.

// Function declarations
int main();

// Function definitions
int main() {
    int n{};

    std::cout << "Enter an integer: ";
    std::cin  >> n;

    if ( n >= 0 ) {
        int result{ n };
    } else {
        int result{ -n };
    }

    std::cout << "The absolute value of "
              << n << " is " << result << std::endl;

    return 0;
}



























// Explanation:
//
// The problem is that 'result' is declared separately
// inside each of the two blocks of the if statement:
//
//     if ( n >= 0 ) {
//         int result{ n };
//     } else {
//         int result{ -n };
//     }
//
// These are actually two different local variables
// that happen to have the same name.
//
// The first 'result' exists only within the block
// following the 'if', while the second 'result'
// exists only within the block following the 'else'.
//
// Consequently, neither variable is in scope when
// the program later tries to execute
//
//     std::cout << ... << result << std::endl;
//
// The solution is to declare 'result' before the
// if statement. It will then remain in scope after
// the if statement has finished executing.
//
// The appropriate value can then be assigned to
// 'result' within each branch.



























// Here is one solution:
/*
int main() {
    int n{};

    std::cout << "Enter an integer: ";
    std::cin  >> n;

    int result{};

    if ( n >= 0 ) {
        result = n;
    } else {
        result = -n;
    }

    std::cout << "The absolute value of "
              << n << " is " << result << std::endl;

    return 0;
}
*/