solve according to the test case given below in c++

3. Write a recursive method called substring that takes as parameters a string, a start index, and an ending index, and that returns a specified substring of the string. You are implementing a recursive alternative to the standard substring method. As with the standard substring method, your method should return the substring that begins at the start index and that extends to the character just before the ending index. For example: substring("hello", 0, 2) should return "he" substring("hamburger", 4, 8) should return "urge" substring("smiles", 1, 5) should return "mile" substring("howdy", 3, 3) should return ""

Test case:(should be true)

//Write test cases for type double TEST(subStr, T1){ string str="he"; EXPECT_EQ(str,substring("hello", 0, 2)); } TEST(subStr, T1){ string str="urge"; EXPECT_EQ(str,substring("hamburger", 4, 8)); }

3. Write a recursive method called substring that takes as parameters a string, a start index, and an ending index, and that returns a specified substring of the string. You are implementing a recursive alternative to the standard substring method. As with the standard substring method, your method should return the substring that begins at the start index and that extends to the character just before the ending index. For example: substring("hello", 0, 2) should return "he" substring("hamburger", 4, 8) should return "urge" substring("smiles", 1, 5) should return "mile" substring("howdy", 3, 3) should return