Why Does Modifying a Call-by-Value Parameter Not Change the Original Variable?

Understanding Call-by-Value Parameter Modification

In the given call-by-value example, a function changeValue is defined and called with an integer argument value initially set to 5. Despite modifying value to 6 within the function, it remains 5 when printed in the main function.

This behavior can be explained by the concept of passing arguments by value. By default, in C/C , function arguments are typically passed by value. When a parameter is passed by value, a copy of the original variable is created and used within the called function. Changes made to the copy do not affect the original variable.

In the provided code, the function changeValue receives the value parameter as a copy. Therefore, any modifications made to value within the function only impact the local copy and not the original variable in main. Consequently, when the value is printed in main, it remains as 5, despite the function's attempt to change it.

To modify the original variable from within the function, call-by-reference is required. By specifying the parameter as a reference, a direct link to the original variable is established, allowing the function to operate directly on it. This ensures that changes made within the function are reflected in the original variable upon returning to main.

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