30+ Programming Interview Questions And Answers
Tags: programming, career, discuss
Published: 2022-11-28 00:03:30

All [large companies](https://www.anythingprogramming.com/2022/01/which-laptop-can-i-use-for-programming.html) are constantly looking for talented [programmers](https://www.anythingprogramming.com/2022/01/how-to-learn-programming-from-zero-to.html) to join their teams. You must acquire as [much knowledge](https://www.anythingprogramming.com/2022/01/which-laptop-can-i-use-for-programming.html) as you can in order to be given an opportunity at these large corporations.

The developer job interview will inevitably include questions on programming. You will always be required to be familiar with [programming basics](https://www.anythingprogramming.com/2022/01/which-laptop-can-i-use-for-programming.html), regardless of the programming language you use. 


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/89vgiuk724hqcga3s715.png)

We've lessened your tension by compiling a list of the top questions that will be asked during programming interviews.
 

**Top Programming Interview Questions and Answers**

To make this easier for you, we've divided the questions into two categories (see below).

1. Concept-based Interview Questions
2. Coding-based Interview Questions

**

## Programming Interview Questions Based on Concept
**


The interview questions in this part will evaluate your comprehension of basic programming concepts.

**What is meant by computer programming? **

Computer programming is a step-by-step process of writing an algorithm using a programming language and executing it.


**Describe an algorithm. What are some of its key characteristics?**


A collection of discrete steps, when followed, aids in the completion of a specific task. Time, Space, and Memory are crucial characteristics of an algorithm.

**Explain Data Abstraction**

Data abstraction is the process of separating the logical structure of data from its physical implementation. Data abstraction allows programmers to create programs that are independent from the physical data structures and that can be used on different types of data.


**What do you understand by maintaining and updating a computer program?**


A computer program's maintenance and update process begin after it has been installed successfully. 

While upgrading a computer program entails making little and significant improvements over time, program maintenance refers to the ongoing activity of checking the program for flaws and mistakes.


**What are Data Structures**


Data structures, It is the method of organizing, sorting and manipulating of data Arrays, Trees, and Graphs are a few of the widely used data structures.


**What exactly is an array?**

A group of objects kept in consecutive memory places is referred to as an array.


**Linked Lists: What Are They?**


A linked list is a linear data structure, similar to an array, where the components aren't always kept together.


**Describe LIFO.**


It is a method for gaining access to, keeping, and retrieving data. Last In First Out is referred to as LIFO.


**Describe FIFO.**


Data can be accessed, saved, and retrieved using this method. First In First Out is referred to as FIFO.


**What is recursion?**


A recursion is function that solves a particular problem by calling a copy of itself and solving smaller subproblems of the original problems.



**Why are Deque used?**


It is possible to have two queues at once. Element removal or insertion from either end is possible in this structure.


**List all possible forms of errors that can happen while a computer program is being run, and explain each one.**


Logical error: Logical error happens when there is a wrong use of syntax and logic in coding. These errors are difficult errors to debug when reports are not generated


Runtime error: Runtime error occurs when there is a wrong code implementation or illegal use of syntax. For instance, dividing a number by 0. Runtime errors are mostly easily debugged errors because they display before executing the program.


Syntax error: Just like every language there is syntax. When these syntaxes are used wrongly there will be an error. Syntax errors are grammatical errors when writing a programming language. Only a compiler can detect syntax errors.


**Describe variables in a few sentences**
 

Variables are containers which stores both data input and produce data output when requested. In reality, these are named memory locations. During the running of the program, the value kept in a variable may change.


**What does the term "Reserved keyword" mean?**


In a certain programming language, reserved keywords are terms with predetermined definitions.


**What do you understand by loops?**


A loop statement that can be repeated a certain number of times until a specified condition is met


**What do constants mean in programming?**


Programming entities called constants to have values that cannot be altered while a program is running.


**Describe the operators.**


In a computer program, operators are employed to carry out certain actions on data. Symbols are used to represent these. For instance, the mathematical symbols / and * stand for division and multiplication, respectively.

** What do you understand by subroutine  **

A subroutine is an identity group or statements that can be used from any location inside an algorithm or a program. 

The control is sent back to the program's subroutine section once the subroutine has successfully completed the task it was designed to accomplish.

**What do you understand by a machine code?**

Machine code is a low-level programming language. It is the most basic form of programming because it consists of ones and zeros. Machine code has been used in the past to program computers. It is still used today to program computers, but it is not as popular as high-level languages like C++ or Java.

**Explain software testing. Why do we need it?**

Software testing is the process of executing a program or system with the intent of finding software bugs

Software testing is an important part of software development because it helps find bugs in the code. 

Some people would say that it's a waste of time and money, but software testing is actually very important to make sure that a product will be delivered to its users without any major issues.


**What do you mean by “beta version” of a computer program?**

The Beta version of a computer program is the second release of a software application that is not yet tested enough to be released to the general public.

The beta version is usually available for free download and will have more features than the previous alpha release. However, there may be bugs and other issues that need to be fixed before it goes live.

**What is a compiler?**

A compiler is a computer program that translates a computer programming language (source code) into another language.

**What is Debugging?**

Debugging is the process of finding and fixing bugs in a program

**Why do we add comments in codes?**

Comments are lines of text that are included in the code to help explain what the code does. Comments can help you remember what you were thinking when you wrote the code, and they can make your programs easier to understand for other people who might need to modify them.

What are some of the best coding practices

Some of the best practices in coding are:
 
1. Use appropriate variables
2. Use functions to make your code more readable
3. Create modular code
4. Comment your code


**

## Programming Interview Questions Based on Code
**

What the code to check a String is palindrome or not? 

```
`#include <string.h>
int main()
{
    char x[2500];  
    int i,n,y=0;
    printf("input string : ");
    gets(x);
    n=strlen(x);
    for(i=0;i<n/2;i++)  
    {
   if(s[i]==x[n-i-1])
   y++;
   }
   if(y==i)
       printf("string is palindrome");
    else
        printf("string is not palindrome");
    return 0;
}`
```

Write a method that will remove any given character from a String?

```
`public class RemoveChar {  
    public static void main(String[] args) {  
              String str = "Visit anythingprogramming.com"; 
              System.out.println(charRemoveAt(str, 7));  
           }  
           public static String charRemoveAt(String str, int p) {  
              return str.substring(0, p) + str.substring(p + 1);  
           }  
}`
```

Print all permutation of String Recursive way? 

```
`public class XYZ {

    static void printPerm(String str, String ans)
    {

        if (str.length() == 0) {
            System.out.print(ans + " ");
            return;
        }
        for (int i = 0; i < str.length(); i++) {

            char ch = str.charAt(i);


            String ros = str.substring(0, i) + 
                         str.substring(i + 1);
            // Recurvise call
            printPerm(ros, ans + ch);
        }
    }
    // Driver code
    public static void main(String[] args)
    {
        String s = "xyz";
        printPermutn(s, "");
    }
}`
 Write a function to find out the longest palindrome in a given string?

` public class Demo {
public static void main(String[] args) {
     Demo lp = new Demo();
     String pal = lp.LongPalindrome("bananas");
        System.out.println("" + pal);    
     pal = lp.LongPalindrome("abaradab121");
        System.out.println("" + pal);
}
public String LongPalindrome(String s) {
     // Validations
     if (s.isEmpty()) {
         return "Please enter a String";
     }
     if (s.length() == 1) {
         return s;
     }
     // Validations end
     // Start with one char (starting) as a longest palindrome
     String longest = s.substring(0, 1);
     for (int i = 0; i < s.length(); i = i+1) {
         // get longest palindrome for odd length (center is i)
         String tmp = checkForEquality(s, i, i);
         if (tmp.length() > longest.length()) {
             longest = tmp;
         }
         // get longest palindrome for even length (center is i, i+1)
         tmp = checkForEquality(s, i, i + 1);
         if (tmp.length() > longest.length()) {
             longest = tmp;
         }
     }
     return longest;
}
public String checkForEquality(String s, int begin, int end) {
     while (begin >= 0 && end <= s.length() - 1 && s.charAt(begin) == s.charAt(end)) {
         begin--;
         end++;
     }
return s.substring(begin + 1, end);
}
} `


```
How to get the matching elements in an integer array?

`

```
for (m = 0; m < size; m++) 
        {
            for (n = m + 1; n < size; n++) 
            {
                if (arry[m] == arry[n]) 
                    System.out.print(arr[m]);
            }
        } `

```
 How to compute the first character of a string that is not repeated?

```
`Set<Character> repeated = new HashSet<>();
List<Character> nonRepeated = new ArrayList<>();
for (int m = 0; m < wrd.length(); m++) {
            char l = wrd.charAt(m);
            if (repeated.contains(l)) {
                continue;
            }
            if (nonRepeated.contains(l)) {
                nonRepeated.remove((Character) l);
                repeated.add(l);
            } else {
                nonRepeated.add(l);
            }
        }
        return nonRepeated.get(0);
    }`
```


How do you get the matching elements in an integer array?

```
int[] a = { 1, 2, 3, 4, 5, 1, 2, 6, 7 };

for (int m = 0; m < a.length; m++) {

    for (int n = m + 1; n < a.length; n++) {

        if (a[m] == a[n])

            System.out.print(a[m]);

    }

}

```
Conclusion

The questions on this list will help you succeed in precise interviews and are ones that any prospective programmer should be familiar with. Please comment if you encounter any other flaws that aren't on this list throughout the interview so that we may include them in the list. Good Luck!