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The standard edition of Problem Set 4 will move beyond C programming language basics, testing your knowledge of pointers, memory management, file i/o and structs.

4 votes
Accepted

pset4 runtime error: unsigned integer overflow

You are subtracting from bi.biWidth on line 125. Since bi.biWidth is an unsigned long, it cannot contain negative values (-1 and so on), instead it's capacity to store positive values is doubled. So b …
Martin Kleiven's user avatar
3 votes
Accepted

How do you pass arguments into GDB argv[1] argv[2]?

To run GDB with arguments in the terminal, use the --args parameter. gdb --args name arg1 arg2 arg3 debug50 (the graphical debugger) is just GDB with a GUI. GDB was originally designed to be run thr …
Martin Kleiven's user avatar
2 votes
2 answers
178 views

Resize is not passing check50, but still properly scaling larger images

I can get smiley.bmp and large.bmp to scale properly, but not small.bmp, where the former is 3x3 and the latter two are larger (exactly how much larger I don't know) -- so I assume my program only wor …
Martin Kleiven's user avatar
1 vote

Pset4 Recover can't find jpg signature

Since your problem is now resolved I'll instead use this answer to explain why what you see happens, and also what memcmp does. I don't understand why uint8_t works but not int uint8_t is guarante …
Martin Kleiven's user avatar
0 votes
1 answer
85 views

PSET 4 recover: segfault when reading buffer

I'm receiving a segfault when reading the first byte (and probably would on the following) of buffer which is a malloced array -- or perhaps not, if unsigned char * doesn't mean what I think it does. …
Martin Kleiven's user avatar
0 votes
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What is peek and how do you use it?

/resize 4 small.bmp student.bmp ~cs50/pset4/resize 4 small.bmp staff.bmp ~cs50/pset4/peek student.bmp staff.bmp Which should let you compare headers of student.bmp and staff.bmp …
Martin Kleiven's user avatar
0 votes
Accepted

Why can't I compile my code?

Have you ensured title is within the scope of main()? It is quite possible you only have it available within the function that previously declared it. Update: I recommend you compile and see for your …
Martin Kleiven's user avatar