Here is a list of 31 important C programs that you should know. These C programs are important for your C programming lab and semester exam.

- Illustrate Pass by Value
- Accept Sorted Array and do Search using Binary Search
- Accepts two Strings & Compare them
- Calculate the Simple Interest
- Calculate the Sum & Difference of the Matrices
- Check if a given Integer is Odd or Even
- Check if a given Matrix is an Identity Matrix
- Check if a given Number is Prime number
- Check if a given String is Palindrome
- Check whether a given Number is Armstrong
- Compute the Product of Two Matrices
- Compute the Sum of Digits in a given Integer
- Find out the Roots of a Quadratic Equation
- Find Reverse of a Number using Recursion
- Find Sum of Digits of a Number using Recursion
- Find the Biggest of 3 Numbers
- Find the Largest Number in an Array
- Find the Nth Fibonacci Number using Recursion
- Find the Transpose of a given Matrix
- Generate Fibonacci Series
- Illustrate Pass by Reference
- Merge the Elements of 2 Sorted Array
- Print Diamond Pattern
- Read an Array and Search for an Element
- Read Two Integers M and N & Swap their Values
- Read two Strings & Concatenate the Strings
- Reverse a Given Number
- Reverse a Number & Check if it is a Palindrome
- Simulate a Simple Calculator
- Sort the Array in an Ascending Order
- Sort the Array in Descending Order