C Functions Practice Problems (original) (raw)
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Last Updated : 18 Oct, 2025
**Functions are the basic building block of C programs. They enhance the modularity and code reusability by separating the logic of a particular task from the main code and using it whenever required.
This article lists a variety of problems based on function concepts such as function definition, return type and parameters, recursion, etc. The list starts with easy problems which gets more difficult as we go down the list.
- Print Hello using Function
- Function to Print Sum
- Function to Return Sum
- Factorial (Using Function)
- Prime Factorization
- Table Difference
- Decimal to Binary
- Binary to Decimal
- Digital Root
- Sum of Digits of a Number
- Fibonacci Using Recursion
Prerequisite
The above problems mainly focus on the C functions, but they also require the knowledge of other basic concepts that are listed below:
If you have some doubts about these concepts, you can revise them from GeeksforGeeks' C Tutorial.
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Basics
- Introduction3 min read
- Identifiers3 min read
- Keywords3 min read
- Variables4 min read
- Data Types4 min read
- Operators8 min read
- Conditional Statements5 min read
- Loops6 min read
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Arrays & Strings
Pointers and Structures
- Pointers7 min read
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- Unions3 min read
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File & Error Handling
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Advanced Concepts
- Variadic Functions4 min read
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- _Generics Keyword3 min read
- Multithreading7 min read
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