String Class - C++ Questions and Answers

This section on online C++ Multiple Choice Questions focuses on “String Class”. One shall practice these questions to improve their C++ programming skills needed for various interviews (campus interviews, walk-in interviews, company interviews), placements, entrance exams and other competitive exams. These questions can be attempted by anyone focusing on learning C++ programming language. They can be a beginner, fresher, engineering graduate or an experienced IT professional. Our C++ questions comes with the detailed explanation of the answers which helps in better understanding of C++ concepts.

Here is a listing of C++ Multiple Choice Questions & Answers focuses on “String Class” along with answers, explanations and/or solutions:

1. How many types of representation are in the string?
a) 1
b) 2
c) 3
d) 4
View Answer

Answer: b
Explanation: C++ provides the following two types of string representations. They are C-style character string and string class type with Standard C++.

2. What is the header file for the string class?
a) #include<ios>
b) #include<str>
c) #include<string>
d) #include<stio>
View Answer

Answer: c
Explanation: #include<string> is the header file for the string class.

3. Which is used to return the number of characters in the string?
a) length
b) size
c) both size & length
d) name
View Answer

Answer: c
Explanation: Both will return the number of characters that conform to the string’s content.

4. What will be the output of the following C++ code?

```
    #include <iostream>
```
```
    #include <cstring>
```
```
    using namespace std;
```
```
    int main ()
```
```
    {
```
```
        char str1[10] = "Hello";
```
```
        char str2[10] = "World";
```
```
        char str3[10];
```
```
        int  len ;
```
```
        strcpy( str3, str1);
```
```
        strcat( str1, str2);
```
```
        len = strlen(str1);
```
```
        cout << len << endl;
```
```
        return 0;
```
```
    }
```

a) 5
b) 55
c) 11
d) 10
View Answer

Answer: d
Explanation: In the program, We are concatenating the str1 and str2 and printing
it’s total length. So the length is 10.
Output:

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$ g++ stri.cpp
$ a.out
10

5. What will be the output of the following C++ code?

```
    #include <iostream>
```
```
    #include <string>
```
```
    using namespace std;
```
```
    int main ()
```
```
    {
```
```
        string str ("microsoft");
```
```
        string::reverse_iterator r;
```

        for (r = str.rbegin() ; r < str.rend(); r++ )

```
            cout << *r;
```
```
        return 0;
```
```
    }
```

a) microsoft
b) micro
c) tfosorcim
d) tfos
View Answer

Answer: c
Explanation: ‘rbegin’ is used to reverse the given the string.
Output:

$ g++ stri1.cpp
$ a.out
tfosorcim

6. What will be the output of the following C++ code?

```
   #include <iostream>
```
```
   #include <string>
```
```
   using namespace std;
```
```
   int main ()
```
```
   {
```

       string str ("nobody does like this");

```
       string key ("nobody");
```
```
       size_t f;
```
```
       f = str.rfind(key);
```
```
       if (f != string::npos)
```

           str.replace (f, key.length(), "everybody");

```
       cout << str << endl;
```
```
       return 0;
```
```
   }
```

a) nobody does like this
b) nobody
c) everybody
d) everybody does like this
View Answer

Answer: d
Explanation: rfind is used to find the characters in the string and replace is used to replace with certain characters.
Output:

$ g++ stri2.cpp
$ a.out
everybody does like this

7. What will be the output of the following C++ code?

```
    #include <iostream>
```
```
    #include <string>
```
```
    using namespace std;
```
```
    int main ()
```
```
    {
```

        string str ("steve jobs is legend");

```
        string::iterator it;
```

        str.erase (str.begin()+ 5, str.end()-7);

```
        cout << str << endl;      
```
```
        return 0;
```
```
    }
```

a) jobs is
b) steve legend
c) steve
d) steve jobs is
View Answer

Answer: b
Explanation: In this program, We are leaving the first 5 characters and last 7 characters and we are erasing the remaining the characters.
Output:

$ g++ stri3.cpp
$ a.out
steve legend

8. What will be the output of the following C++ code?

```
    #include <iostream>
```
```
    #include <string>
```
```
    using namespace std;
```
```
    int main ()
```
```
    {
```
```
        string str ("Microsoft");
```

        for (size_t i = 0; i < str.length();)

```
        {
```
```
            cout << str.at(i-1);
```
```
        }
```
```
        return 0;
```
```
    }
```

a) M
b) Microsoft
c) Micro
d) runtime error
View Answer

Answer: d
Explanation: This program will terminate because the cout element is out of range.

9. What will be the output of the following C++ code?

```
   #include <iostream>
```
```
   #include <string>
```
```
   using namespace std;
```
```
   int main ()
```
```
   {
```
```
       string str ("Ubuntu");
```
```
       cout << str.capacity();
```
```
       cout << str.max_size();
```
```
       return 0;
```
```
   }
```

a) 61073741820
b) 51073741820
c) 6 and max size depends on compiler
d)

15
9223372036854775807

View Answer

Answer: d
Explanation: str.capacity() returns the size of the storage space currently allocated for the string, expressed in terms of bytes and capacity of the string may be equal or greater. The max_size() returns the max size of the string.
Output:

$ g++ stri5.cpp
$ a.out
15
9223372036854775807

10. Which method do we use to append more than one character at a time?
a) append
b) operator+=
c) data
d) both append & operator+=
View Answer

Answer: d
Explanation: C++ allows to append more characters to string using both inbuilt append() function and using operator overloaded += operator.

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