string manipulation in c interview questions

reddit.com › r/cprogramming › most commonly asked string questions in c.

r/cprogramming on Reddit: Most commonly asked string questions in C.

November 20, 2023 -

Hello Everyone,

I am currently interviewing for Embedded/Firmware-related jobs. Strings are not my strongest suit. So far, I have been asked to check if a given string is a palindrome or not. However, since I started doing LeetCode, I have been struggling the most with string-related questions, especially those involving substrings.

What have been the most common interview questions you've been asked, particularly those involving strings?

Top answer

1 of 5

I've never really found strings hard. The key is that strings don't exist. Arrays of char exist. The standard library expects a "string" to end with the null character '\0. If a string is a palindrome then the last character is the same as the first, the second last character is the same as the second, repeat that until you hit the halfway point. You might find it useful to look over the string FAQs at https://c-faq.com/ and read some documentation on string.h header: https://www.geeksforgeeks.org/c-library-string-h/ https://en.cppreference.com/w/c/string/byte Write programs which exercise every function.

2 of 5

I worked in firmware. very little string manipulation are required. Usually for logging, sprintf or better snprintf (no memory allocation, use a static buffer). Other common situation is a command parser (common interview question), you just need to tokenize the string based on delimiter (either strtok, or roll your own). Sometime, some device reply with ascii (ex, NMEA for Gps), so you need some parsing. instead of Leetcode questions, do a small exercice. Write your own small command interpreter. This will teach how to parse string and format a response.

HackerRank

hackerrank.com › interview › interview-preparation-kit › strings › challenges

Solve String Manipulation Interview Questions | HackerRank

Please read our cookie policy for more information about how we use cookies. Ok · Prepare · Interview Preparation Kit · String Manipulation · How many characters should one delete to make two given strings anagrams of each other?

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IndiaBIX

indiabix.com › technical › c › strings

Strings - C Programming Interview Questions and Answers

This has the effect of right-justifying the input string. Finally, because the strdup() function dynamically allocates memory, the free() function is called to free up the memory taken by the duplicate string. Check out the latest current affairs questions and answers. Check out the latest interview questions and answers.

Aticleworld

aticleworld.com › home › top 15 string interview questions in c, might ask by the interviewer.

Top 15 string Interview Questions in C, might ask by the interviewer. - Aticleworld

January 1, 2020 - Suppose if input string is pString , pString = “silence is a source of great strength” ; /* input string */ ... Copy the *(pString + startIndex) character in resultant string.

w3resource

w3resource.com › c-programming-exercises › string › index.php

C programming exercises: String - w3resource

Test Data : Check the length of two strings: -------------------------------- Input the 1st string : aabbcc Input the 2nd string : abcdef String1: aabbcc String2: abcdef Expected Output : Strings are not equal.

GeeksforGeeks

geeksforgeeks.org › dsa › top-50-string-coding-problems-for-interviews

String Coding Interview Questions - GeeksforGeeks

September 18, 2025 - String-related problems often assess a candidate's understanding of concepts like pattern matching, manipulation, and efficient algorithm design. Here is the collection of frequently asked interview questions on Strings. Problems in this Article are divided into three Levels so that readers ...

Oops Info Solutions

oopsinfosolution.com › home › string interview questions

String Interview Questions | Oops Info Solutions Pvt. Ltd.

November 7, 2017 - Knowing answers to these questions will be very helpful to tackle any questions asked related to String in interview. int main() { char str[1000], ch; int i, freQuency = 0; printf("Enter a string: "); gets(str); printf("Enter a character to find the frequency: "); scanf("%c",&ch); for(i = 0; str[i] != '\0'; ++i) { if(ch == str[i]) ++freQuency; } printf("Frequency of %c = %d", ch, frequency); return 0; }

Techie Delight

techiedelight.com › home › string – interview questions and practice problems

String – Interview Questions and Practice Problems | Techie Delight

September 12, 2025 - Find the longest even-length palindromic sum substring of a stringMedium ... Average rating 4.82/5. Vote count: 56 · No votes so far! Be the first to rate this post. We are sorry that this post was not useful for you! Tell us how we can improve this post? Submit Feedback ... Thanks for reading. To share your code in the comments, please use our online compiler that supports C, C++, Java, Python, JavaScript, C#, PHP, and many more popular programming languages.

Medium

medium.com › @akabaridixit009 › top-string-coding-interview-questions-and-answers-part-1-ac46cf964cc7

Top String Coding Interview Questions and Answers | Medium

August 29, 2024 - Input: let str1 = "listen" let str2 = "silent" Expected Output: True Input: let str1 = "allergy" let str2 = "allergic" Expected Output: False ... This approach sorts the characters of both strings and compares the sorted versions.

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Google Bing Mojeek

reddit.com › r/cscareerquestions › string manipulation questions

r/cscareerquestions on Reddit: String manipulation questions

May 3, 2024 -

Howdy! I have an interview coming up in 2 weeks and wanted to practice string manipulation(as it was hinted that’s what I’d be tested on).

I’ve practiced a few already but mostly been seeing similar 2 pointer ones. Does anyone have any other questions they recommend to just practice string manipulation or string parsing that isn’t the typical reverse a string?

I’m trying to compile a few more problems to practice and hope to be ready.

Top answer

1 of 1

Hey! Aside from the typical "reverse a string" problems, you might want to try these: Group of Anagrams String Palindromes Permutation Palindrome These should give you a good variety to practice! Here's a full list of string manipulation problems you might want to try. Hope this helps!

Stack Overflow

stackoverflow.com › questions › 42900269 › interview-questions-about-string-and-char

c - Interview questions about string and char - Stack Overflow

Top answer

1 of 3

Both results in undefined behaviour.

The first is because you are using a pointer (str) after free'ing it (free() doesn't/can't set the pointer to NULL after being the block).

The second because you are using a pointer to a local variable from another function.

2 of 3

Both examples contain the same type of error, using an object after its lifetime has ended.

Doing so results in undefined behavior¹. The text uses the word 'referred', which basically means accessing an object or using an identifier of said object.

What actually causes undefined behavior in both examples isn't the rule mentioned above¹, but another one, which is closely related. The value of a pointer which points to an object whose lifetime has ended is indeterminate². Reading such values causes undefined behavior. This happens in both examples.

In the first example, the lifetime of str ends at the call to free. The pointer is then used in the if statement if(str != NULL){ which causes undefined behavior.

In the second example, the lifetime of p ends when the function returns. The returned pointer is assigned to a pointer str: str = GetMemory();, which causes undefined behavior.

¹ (Quoted from: ISO/IEC 9899:201x 6.2.4 Storage durations of objects 2)
If an object is referred to outside of its lifetime, the behavior is undefined.

² (Quoted from: ISO/IEC 9899:201x 6.2.4 Storage durations of objects 2)
The value of a pointer becomes indeterminate when the object it points to (or just past) reaches the end of its lifetime.

Technoname

technoname.com › home › string coding questions with solutions.

String Coding Questions with solutions. - Technoname

September 29, 2021 - This blog covers all the string coding questions might be asked in any of your interviews or coding round and will improve practical knowledge.

Quora

quora.com › What-are-the-most-important-string-manipulation-questions-every-Computer-Science-student-should-know

What are the most important string manipulation questions every Computer Science student should know? - Quora

Some good questions on string manipulation are: 1. Check if string is palindrome or not 2. Reverse a string without recursion and temp space. 3. Finding a substring in a String with best space and time complexity.

GeeksforGeeks

geeksforgeeks.org › c++ › string-c-cpp-programs

String C/C++ Programs - GeeksforGeeks

July 23, 2025 - C/C++ Program for Remove characters from the first string which are present in the second string C/C++ Program for A Program to check if strings are rotations of each other or not C/C++ Program for Print reverse of a string using recursion C/C++ ...

Tech Interview Handbook

techinterviewhandbook.org › string

String cheatsheet for coding interviews | Tech Interview Handbook

Ask about input character set and case sensitivity. Usually the characters are limited to lowercase Latin characters, for example a to z. ... Many string questions fall into one of these buckets.

Stack Overflow

stackoverflow.com › questions › 2635234 › classic-string-manipulation-interview-questions

Classic string manipulation interview questions? - Stack Overflow

Top answer

1 of 7

They might ask you about regular expressions. If they are using Java, they might ask the difference of StringBuffer and StringBuilder.

2 of 7

Reverse words in a sentence, e.g.

"string manip interview question"

becomes

"question interview manip string"

this has a solution that uses only one char worth of temporary space.

LeetCode

leetcode.com › discuss › interview-question › 6000382 › Most-Common-String-Interview-Problems

Most Common String Interview Problems - Discuss - LeetCode

Key Skill: Clean string manipulation and pointer techniques.

Medium

medium.com › javarevisited › top-21-string-programming-interview-questions-for-beginners-and-experienced-developers-56037048de45

Top 21 String Programming Interview Questions for Beginners and Experienced Developers | by javinpaul | Javarevisited | Medium

2 weeks ago - In this article, I am going to share some of the most common String based coding problems I have come across from many Programming interviews I have been part of. I also have experience from both sides of the table as a candidate as well as the Interviewer, so I know how important these questions are.

Naukri

naukri.com › code360 › problem-lists › top-string-coding-interview-questions