String Data Structure Quiz for Beginners

Last Updated : 25 Sep, 2023

Strings are considered a data type in general and are typically represented as arrays of bytes (or words) that store a sequence of characters. Strings are defined as an array of characters. The difference between a character array and a string is the string is terminated with a special character ‘\0’.
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String Data Structure

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Question 1

What is the output of the following code?

C++

#include <iostream>
using namespace std;

int main()
{

    string str1 = "Hello";
    string str2 = "Geeks";
    string str3 = str1 + str2;
    cout << str3 << endl;

    return 0;
}

	Hello + Geeks
	str1 + str2
	Hello Geeks
	HelloGeeks

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Question 1-Explanation:

"+" operator is used to concatenate two string , so the str1 and str2 is concatenated into third string.

Hence, Option (D) is the correct answer.

Question 2

What is the output of the following code?

C++

#include <iostream>
using namespace std;

int main()
{

    string str = "Hello";
    cout << str.substr(2, 5);
    return 0;
}

	Syntax error
	ello
	llo
	None

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Question 2-Explanation:

The substr function takes two values pos and len as an argument and returns a newly constructed string object with its value initialized to a copy of a sub-string of this object. Copying of string starts from pos and is done till pos+len means [pos, pos+len).

pos: Position of the first character to be copied.
len: Length of the sub-string.

So str.substr(2, 5) will copy the characters from index 2 to 4. which is llo.

Hence (C) is the correct answer.

Question 3

What is the output of the following code?

C++

#include<bits/stdc++.h> 
using namespace std;

int main()
{
    // Write C++ code here
    char str_array2[] = "Geeks";
    cout << sizeof(str_array2) << " ";
    char str_array[] = { 'G', 'e', 'e', 'k', 's'};
    cout << sizeof(str_array);
    return 0;
}

	6, 6
	5, 6
	6, 5
	None

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Question 3-Explanation:

when we are initializing a char array as a value of the string, then C++ automatically adds a null character at the end of the string, and the size of the char array is increased by one.

eg: char str_array2[] = "Geeks"; // the length of the array is 6 here.

But when we are initializing a char array in the form of sequence of characters, then the size of the char array is the number of characters present in the array.

eg: char str_array[] = { 'G', 'e', 'e', 'k', 's'}; // the length of the array is 5 here.

Hence Option (C) is the correct answer.

Question 4

If two string s are identical, then strcmp() functions returns ______

	-1
	1
	YES
	0

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Question 4-Explanation:

If two strings are identical, then strcmp() functions returns 0.

The strcmp() function returns three different values after the comparison of the two strings which are as follows:

A value equal to zero when both strings are found to be identical. That is, all of the characters in both strings are the same.
A value greater than zero is returned when the first not-matching character in first_str has a greater ASCII value than the corresponding character in second_str or we can also say that if the character in first_str is lexicographically after the character of second_str, then zero is returned.
A value less than zero is returned when the first not-matching character in first_str has a lesser ASCII value than the corresponding character in second_str. We can also say that if the character in first_str is lexicographically before the character of second_str, zero is returned.

Hence Option (C) is correct.

Question 5

How will you print "\n" on the screen?

	cout << "\\\n";
	cout<<"\\\\\n";
	cout<<"//n";
	cout<<"///n"

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Question 5-Explanation:

The statement cout << "\\\n"; will print \n on the screen.

Hence (A) is the correct option.

Question 6

What will the output of the following questions:

C++

#include <bits/stdc++.h>
using namespace std;

int main()
{

    string a = "Hello";
    string b = "World";
    string c = b.append(a);
    cout << c << endl;

    return 0;
}

	Hello world
	World hello
	WorldHello
	Error

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Question 6-Explanation:

append function will append the characters of string a into b.

For more Reference Please visit:
https://www.geeksforgeeks.org/stdstringappend-in-c/

Hence Option(C) is correct.

Question 7

What is missing in the given code?

C++

#include <bits/stdc++.h>
using namespace std;

void reverseStr(string& str)
{

    for (int i = 0; i < n / 2; i++)
        swap(str[i], str[n - i - 1]);
}

// Driver program
int main()
{
    string str = "geeksforgeeks";
    reverseStr(str);
    cout << str;
    return 0;
}

	swap function is not defined
	string is not defined here.
	Variable n is not declared anywhere.
	None

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Question 7-Explanation:

Variable n is the size of the string here, which is not defined here. the correct code will be as follow:

C++

#include using namespace std; void reverseStr(string& str) { int n = str.length(); for (int i = 0; i < n / 2; i++) swap(str[i], str[n - i - 1]); } // Driver program int main() { string str = "geeksforgeeks"; reverseStr(str); cout << str; return 0; }[/sourcecode][tabbyending]

Hence (C) is the correct Option.

Question 8

What is the function present to sort a string in C++?

	sort();
	sort(str.begin(), str.end());
	Sort_asec();
	None

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Question 8-Explanation:

sort(str.begin(), str.end()); is the syntax for sorting the string in C++.

For more reference, Please visit:
https://www.geeksforgeeks.org/sort-string-characters/

Hence Option(B) is the correct answer.

Question 9

What is the below image explaining?

	The image is about the substring of a string
	The image is about the subsequence of a string
	The image is about arrays.
	None

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Question 9-Explanation:

The above image is about the subsequences of a string.

Subsequences of String

Hence Option (B) is the correct answer.

Question 10

What is a palindromic string?

	The string of length 0
	The string of having a special character.
	The string of having an uppercase letter
	The string whose reversed string is equal to the original string.

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Question 10-Explanation:

A string is called a palindrome if the reverse of the string is the same as the original one. For example, “madam”, “racecar”, and “12321”.

Hence Option (D) is correct.

1 2

There are 20 questions to complete.

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