C PRACTICE
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Work through focused C exercises from approachable foundations to more demanding problem-solving patterns.
11C exercises
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C EXERCISES
Every level includes clear requirements and a solution-file reference tab.Choose your level
beginner
4 exercisesBeginner · build the foundation
Start with one core idea at a time and make the basic moves feel automatic.
01020304
Cbeginner
Count vowels in a C string
Return the number of English vowels in a null-terminated string. Count upper- and lower-case letters, and treat a null pointer as an empty string.
Cbeginner
Find the maximum safely
Implement find_max to write the greatest array value into out. Return 1 on success and 0 when the array is empty, the pointer is null, or out is null.
Cbeginner
Sum an integer array safely
Implement sum_array so it returns the sum of exactly length elements. The caller owns the array; handle a null pointer or zero length without dereferencing it.
Cbeginner
Swap two integers through pointers
Implement swap_ints so the caller's two integer variables exchange values. It must do nothing when either pointer is null.
intermediate
4 exercisesIntermediate · connect the pieces
Combine concepts, validate inputs, and make practical design decisions.
01020304
Cintermediate
Copy a string with a capacity contract
Write copy_string that copies source into destination when capacity is non-zero, always terminates the destination, and reports failure if the source will not fit.
Cintermediate
Deduplicate a sorted integer array
Remove duplicates in-place from an ascending integer array and return the number of unique values. The retained prefix must preserve ascending order.
Cintermediate
Grow a dynamic integer buffer
Implement append_int so a heap-backed buffer grows geometrically, checks multiplication overflow, and leaves the original allocation untouched if realloc fails.
advanced
3 exercisesAdvanced · handle real-world constraints
Work with edge cases, maintainability, and the tradeoffs found in production code.
010203
Cadvanced
Audit a multi-file build
Given app.c, inventory.c, inventory.h, and Makefile, explain and write the dependency rules needed so changing inventory.h recompiles both relevant object files before linking.
Cadvanced
Parse one CSV inventory record
Parse a simple inventory record in the form id,name,quantity into a struct. Reject missing fields, extra commas, an empty name, and a quantity outside 0..100000.
Cadvanced
Push into a bounded ring queue
Implement queue_push for a fixed-capacity circular queue. Return 0 when the queue is full or invalid; otherwise store the value, advance tail with wraparound, and increase size.
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