Why Does Pointer Assignment in Go Functions Sometimes Not Affect the Original Value?

Pointer Assignment in Go Functions: Why Different Outcomes?

When passing a pointer to a function in Go, it's crucial to understand how the pointer is used and the implications it has on the original value. This discussion revolves around a code snippet that passes a pointer to a struct Test, intending to modify its Value field.

The first code snippet, despite attempting to change the Value field by assigning a new Test struct to the pointer (*p = Test{4}), fails to alter the actual value. This is because it merely reassigns the pointer variable p, not the pointed value. The p variable within the f() function exists independently and has no impact on the value pointed to by the p variable in main().

In contrast, the second code snippet, where p.Value is explicitly set to 4, successfully modifies the Value field. This is because the operator dereferences the pointer, allowing access and modification of the actual pointed value.

As an additional note, it's possible to modify the address stored in the main() function's pointer variable by passing its address (*) to the f() function. However, this approach is less efficient and convenient compared to directly modifying the pointed value using p.Value.

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