string - The difference between t and *t

Question

package main

import "fmt"

type TT struct {
    a int
    b float32
    c string
}

func (t *TT) String() string {
    return fmt.Sprintf("%+v", *t)
}

func main() {
    tt := &TT{3, 4, "5"}
    fmt.Printf(tt.String())
}

The code can work well. But if I change the String method as in the following, it will cause dead loop. The difference is that the *t is replaced with t. Why?

func (t *TT) String() string {
    return fmt.Sprintf("%+v", t)
}

Answer 1

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