Zero value in Golang - GeeksforGeeks

In Go language, whenever we allocate memory for a variable with the help of declaration or by using new and if the variable is not initialized explicitly, then the value of such types of variables are automatically initialized with their zero value. The initialization of the zero value is done recursively. So, every element of the array of the structs has its fields zero if they are not specified with any value. Following are the zero values for different types of variables:

Type	Zero Value
Integer	0
Floating point	0.0
Boolean	false
String	“”
Pointer	nil
Interface	nil
Slice	nil
Map	nil
Channel	nil
Function	nil

Example 1:

// Go program to illustrate the concept of zero value 
package main 
  
import "fmt"
  
// Main Method 
func main() { 
  
    // Creating variables 
    // of different types 
    var q1 int
    var q2 float64 
    var q3 bool
    var q4 string 
    var q5 []int
    var q6 *int
    var q7 map[int]string 
  
    // Displaying the zero value 
    // of the above variables 
    fmt.Println("Zero value for integer types: ", q1) 
    fmt.Println("Zero value for float64 types: ", q2) 
    fmt.Println("Zero value for boolean types: ", q3) 
    fmt.Println("Zero value for string types: ", q4) 
    fmt.Println("Zero value for slice types: ", q5) 
    fmt.Println("Zero value for pointer types: ", q6) 
    fmt.Println("Zero value for map types: ", q7) 
} 

Output:

Zero value for integer types:  0
Zero value for float64 types:  0
Zero value for boolean types:  false
Zero value for string types:  
Zero value for slice types:  []
Zero value for pointer types:  <nil>
Zero value for map types:  map[]

Example 2:

// Go program to check the variable 
// contains zero value or not 
package main 
  
import "fmt"
  
func main() { 
  
    // Creating variables of different types 
    var q1 int = 2 
    var q2 float64 
    var q3 bool
    var q4 string 
  
    // Slice 
    var q5 []int
  
    // Pointer 
    var q6 *int
  
    // Map 
    var q7 map[int]string 
  
    // Checking if the given variables 
    // contain their zero value or not 
    if q1 == 0 { 
      
        fmt.Println("True") 
          
    } else { 
      
        fmt.Println("False") 
    } 
  
    if q2 == 0 { 
      
        fmt.Println("True") 
          
    } else { 
      
        fmt.Println("False") 
    } 
  
    if q3 == false { 
      
        fmt.Println("True") 
          
    } else { 
        fmt.Println("False") 
    } 
  
    if q4 == "" { 
      
        fmt.Println("True") 
          
    } else { 
      
        fmt.Println("False") 
    } 
  
    if q5 == nil { 
      
        fmt.Println("True") 
          
    } else { 
      
        fmt.Println("False") 
    } 
  
    if q6 == nil { 
      
        fmt.Println("True") 
          
    } else { 
      
        fmt.Println("False") 
    } 
  
    if q7 == nil { 
      
        fmt.Println("True") 
          
    } else { 
      
        fmt.Println("False") 
    } 
  
} 

Output:

False
True
True
True
True
True
True

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