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strings.Contains and ContainsAnyUse the Contains and ContainsAny funcs in the strings package to find substrings in strings.
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This page was last reviewed on Jul 21, 2023.
Contains. Is one string contained in another? With Contains we search one string for a certain substring. We see if the string is found.
With other funcs like ContainsAny we search for characters. If any of a set of characters is found in the string, ContainsAny will return true.
strings.Index
First example. We have a string that contains "this is a test." The word "test" is found in the string. When we invoke Contains and search for "test," we receive true.
Argument 1 The first argument to Contains is a string. It is the string we are searching inside.
Argument 2 The second argument is the value we are searching for within the first argument.
package main import ( "fmt" "strings" ) func main() { value1 := "test" value2 := "python" source := "this is a test" // This succeeds. // ... The substring is contained in the source string. if strings.Contains(source, value1) { fmt.Println(1) } // Contains returns false here. if !strings.Contains(source, value2) { fmt.Println(2) } }
1 2
ContainsAny. This method is different from Contains—it searches for characters. If any of the values in the second string argument to ContainsAny are found, it returns true.
Argument 1 The first argument to ContainsAny is the string we are searching for values within.
Argument 2 This is a set of values—just one has to be found for the method to return true.
package main import ( "fmt" "strings" ) func main() { source := "12345" // See if 1, 3 or 5 are in the string. if strings.ContainsAny(source, "135") { fmt.Println("A") } // See if any of these 3 chars are in the string. if strings.ContainsAny(source, "543") { fmt.Println("B") } // The string does not contain a question mark. if !strings.ContainsAny(source, "?") { fmt.Println("C") } }
A B C
Contains is clearer than Index() when we just need to test existence. We can test against true and false, not the magical value -1 that Index() returns to mean "not found."
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This page was last updated on Jul 21, 2023 (edit).
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