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Master the fundamental concepts of c programming deep dive through this focused micro-challenge.
The sizeof operator reports how many bytes a type or expression occupies. Clang and GCC evaluate it at compile time, which is why you can size static buffers and pass sizeof(int) * n to malloc without a runtime lookup. On a typical Linux x86-64 ABI, int is 4 bytes, long is 8 bytes, and every pointer is 8 bytes no matter what it points at.
Struct layout is not always the sum of field sizes. Compilers insert padding so each member aligns to its natural boundary. An int followed by a char often becomes 8 bytes, not 5. String literals include a null terminator, so sizeof("hello") is 6. Array sizes multiply: int[10] is 40 bytes when int is 4.
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On x86-64 you typically see int: 4 and struct: 8 because of trailing padding.
For this exercise, you will print sizes for primitives, pointers, arrays, a struct, and a few expressions. This task asks you to treat sizeof as a diagnostic tool: once you know real sizes on your platform, stack allocation and heap requests stop being guesswork.
Every C type has a size fixed by the platform ABI, and sizeof reports it at compile time. Print the sizes of the basic types, of pointers, of arrays, of a small struct, and of two expressions, on x86-64 Linux (the LP64 model the judge uses).
One word selecting which group to print: basic, pointers, arrays, struct or all. Empty input means all.
Each line has the form NAME: N bytes, printed with %zu:
| mode | lines, in order |
|---|---|
basic | char, short, int, long, long long, float, double |
pointers | int*, char*, double* |
arrays | int[10], char[10], double[5] |
struct | struct: N bytes for struct { int a; char b; }, then sizeof(2 + 3.5): N and sizeof("hello"): N (these two lines have no "bytes") |
all | every group above, in that order, then All sizes printed correctly |
Input:
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Output:
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sizeof. Don't hard-code the numbers.size_t with %zu.Hidden tests cover the pointer, array and struct groups, and the full report.
Three hints are available for this task, revealed one at a time inside the code workspace so you can struggle productively before seeing them.
Every task includes starter code, theory, and hidden tests so you can implement and verify locally in the browser.
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