| Go supports <em><a href="http://en.wikipedia.org/wiki/Pointer_(computer_programming)">pointers</a></em>, allowing you to pass references to values and records within your program. | ||
package main |
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import "fmt" |
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| We'll show how pointers work in contrast to values with 2 functions: `zeroval` and `zeroptr`. `zeroval` has an `int` parameter, so arguments will be passed to it by value. `zeroval` will get a copy of `ival` distinct from the one in the calling function. | func zeroval(ival int) { |
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ival = 0 |
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} |
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| `zeroptr` in contrast has an `*int` parameter, meaning that it takes an `int` pointer. The `*iptr` code in the function body then _dereferences_ the pointer from its memory address to the current value at that address. Assigning a value to a dereferenced pointer changes the value at the referenced address. | func zeroptr(iptr *int) { |
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*iptr = 0 |
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} |
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func main() { |
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i := 1 |
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fmt.Println("initial:", i) |
initial: 1 |
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zeroval(i) |
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fmt.Println("zeroval:", i) |
zeroval: 1 |
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| The `&i` syntax gives the memory address of `i`, i.e. a pointer to `i`. | zeroptr(&i) |
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fmt.Println("zeroptr:", i) |
zeroptr: 0 |
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| Pointers can be printed too. | fmt.Println("pointer:", &i) |
pointer: 0xc00001c198 |
} |