How to find the capacity of Channel, Pointer and Slice in Golang?

Last Updated : 10 May, 2020

Go language, capacity defines the maximum number of elements that a particular can hold. Here the task is to find the capacity of Channel, Pointer, and Slice in Golang, we can use the cap() function.

Syntax:

func cap(l Type) int

Here, the type of l is a pointer.

Let us discuss this concept with the help of the examples:

Example 1: In this example, cap() function is used to find the capacity of Pointer in Golang.

// Go program to illustrate how to find the  
// capacity of the pointer  
package main  
    
import (  
    "fmt"
)  
    
// Main function  
func main() {  
    
    // Creating and initializing  
    // pointer 
    // Using var keyword  
    var ptr1 [7]*int
    var ptr2 [5]*string  
    var ptr3 [8]*float64  
    
    // Finding the capacity of  
    // the pointer 
    // Using cap function  
    fmt.Println("Capacity of ptr1: ", cap(ptr1))  
    fmt.Println("Capacity of ptr2: ", cap(ptr2))  
    fmt.Println("Capacity of ptr3: ", cap(ptr3))  
    
}  

Output:

Capacity of ptr1:  7
Capacity of ptr2:  5
Capacity of ptr3:  8

Example 2: In this example, cap() function is used to find the capacity of Channel in Golang.

// Go program to illustrate how to find the  
// capacity of the Channel 
package main  
    
import (  
    "fmt"
)  
    
// Main function  
func main() {  
    
    // Creating and initializing  
    // Channel 
    // Using var keyword  
    ch1 := make(chan int, 7)  
    ch2 := make(chan string, 5) 
    ch3 := make(chan float64, 8) 
    
    // Finding the capacity of  
    // the Channel 
    // Using cap function  
    fmt.Println("Capacity of Channel1: ", cap(ch1))  
    fmt.Println("Capacity of Channel2: ", cap(ch2))  
    fmt.Println("Capacity of Channel3: ", cap(ch3))  
    
}  

Output:

Capacity of Channel1:  7
Capacity of Channel2:  5
Capacity of Channel3:  8

Example 3: In this example, cap() function is used to find the capacity of Slice in Golang.

// Go program to illustrate how to find the  
// capacity of the Slice  
package main  
    
import (  
    "fmt"
)  
    
// Main function  
func main() {  
    
    // Creating and initializing  
    // Slice  
    // Using var keyword  
    sl1 := make([]int, 0, 7)  
    sl2 := make([]string, 0, 5) 
    sl3 := make([]float64, 0, 8) 
    
    // Finding the capacity of  
    // the Slice  
    // Using cap function  
    fmt.Println("Capacity of Slice1: ", cap(sl1))  
    fmt.Println("Capacity of Slice2: ", cap(sl2))  
    fmt.Println("Capacity of Slice3: ", cap(sl3))  
    
} 

Output:

Capacity of Slice1:  7
Capacity of Slice2:  5
Capacity of Slice3:  8

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