How to trim left-hand side of a slice of bytes in Golang?

Last Updated : 26 Aug, 2019

In Go language slice is more powerful, flexible, convenient than an array, and is a lightweight data structure. The slice is a variable-length sequence which stores elements of a similar type, you are not allowed to store different type of elements in the same slice.
In the Go slice of bytes, you are allowed to trim all the starting UTF-8-encoded code points from the given slice using TrimLeft() function. This function returns a subslice of the original slice by slicing off all the leading UTF-8-encoded code points which are specified in the given string. If the given slice of bytes does not contain the specified string in its left-hand side, then this function returns the original slice without any change. It is defined under the bytes package so, you have to import bytes package in your program for accessing TrimLeft function.

Syntax:

func TrimLeft(ori_slice[]byte, cut_string string) []byte

Here, ori_slice is the original slice of bytes and cut_string represent a string which you want to trim in the given slice. Let us discuss this concept with the help of the given examples:

Example 1:

// Go program to illustrate the concept 
// of left trim in the slice of bytes 
package main 
  
import ( 
    "bytes"
    "fmt"
) 
  
func main() { 
  
    // Creating and initializing 
    // the slice of bytes 
    // Using shorthand declaration 
    slice_1 := []byte{'!', '!', 'G', 'e', 'e', 'k', 's', 'f', 
                 'o', 'r', 'G', 'e', 'e', 'k', 's', '#', '#'}  
      
    slice_2 := []byte{'*', '*', 'A', 'p', 'p', 'l', 'e', '^', '^'} 
      
    slice_3 := []byte{'%', 'g', 'e', 'e', 'k', 's', '%'} 
  
    // Displaying slices 
    fmt.Println("Original Slice:") 
    fmt.Printf("Slice 1: %s", slice_1) 
    fmt.Printf("\nSlice 2: %s", slice_2) 
    fmt.Printf("\nSlice 3: %s", slice_3) 
  
    // Trimming specified leading Unicodes  
    // points from the given slice 
    // Using TrimLeft function 
    res1 := bytes.TrimLeft(slice_1, "!#") 
    res2 := bytes.TrimLeft(slice_2, "*") 
    res3 := bytes.TrimLeft(slice_3, "@") 
  
    // Display the results 
    fmt.Printf("\n\nNew Slice:\n") 
    fmt.Printf("\nSlice 1: %s", res1) 
    fmt.Printf("\nSlice 2: %s", res2) 
    fmt.Printf("\nSlice 3: %s", res3) 
  
} 

Output:

Original Slice:
Slice 1: !!GeeksforGeeks##
Slice 2: **Apple^^
Slice 3: %geeks%

New Slice:

Slice 1: GeeksforGeeks##
Slice 2: Apple^^
Slice 3: %geeks%

Example 2:

// Go program to illustrate the concept 
// of left trim in the slice of bytes 
package main 
  
import ( 
    "bytes"
    "fmt"
) 
  
func main() { 
  
    // Creating and trimming 
    // the slice of bytes 
    // Using TrimLeft function 
    res1 := bytes.TrimLeft([]byte("****Welcome to GeeksforGeeks****"), "*") 
    res2 := bytes.TrimLeft([]byte("!!!!Learning how to trim a slice of bytes@@@@"), "!@") 
    res3 := bytes.TrimLeft([]byte("^^Geek&&"), "$") 
  
    // Display the results 
    fmt.Printf("\nFinal Slice:\n") 
    fmt.Printf("\nSlice 1: %s", res1) 
    fmt.Printf("\nSlice 2: %s", res2) 
    fmt.Printf("\nSlice 3: %s", res3) 
} 

Output:

Final Slice:

Slice 1: Welcome to GeeksforGeeks****
Slice 2: Learning how to trim a slice of bytes@@@@
Slice 3: ^^Geek&&

Suggest improvement

Golang | Checking the byte of slice for specified regular expression

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