BiteSizedChunks.comLearn one small thing at a time.

Course contentsShow

840Testing for alphabetic characters with `isalpha`
841Checking for digits with `isdigit` and `isxdigit`
842Identifying whitespace with `isspace`
843Distinguishing `ispunct` and `isgraph`
844Case testing with `isupper` and `islower`
845Converting case with `toupper` and `tolower`
846The importance of casting to `unsigned char` in `ctype` functions
847Finding string length with `strlen`
848Copying strings safely with `strncpy`
849Concatenating strings with `strncat`
850Lexicographical comparison with `strcmp`
851Searching for characters with `strchr` and `strrchr`
852Finding substrings with `strstr`
853Tokenizing strings with `strtok`
854Understanding the `strcoll` and `strxfrm` locale functions
855Setting memory blocks with `memset`
856Copying memory with `memcpy`
857Handling overlapping regions with `memmove`
858Comparing memory blocks with `memcmp`
859Searching memory bytes with `memchr`
860Performance differences between `str` and `mem` functions
861Basic power and square root: `pow` and `sqrt`
862Exponential and logarithmic functions: `exp`, `log`, `log10`
863Trigonometric functions in radians
864Rounding with `ceil`, `floor`, and `round`
865Truncation and remainder: `trunc` and `fmod`
866Absolute values for floats with `fabs`
867Handling `NAN` and `INFINITY` constants
868Allocating memory with `malloc` and `free`
869Contiguous allocation with `calloc`
870Resizing blocks with `realloc`
871Converting strings to integers with `atoi` and `atol`
872Robust string-to-number conversion with `strtol`
873Converting strings to doubles with `strtod`
874Communicating with the OS using `system`
875Cleaning up at exit with `atexit`
876The generic signature of `qsort`
877Writing an integer comparison function
878Writing a string comparison function for `qsort`
879Sorting structs by multiple fields
880Using `bsearch` on sorted arrays
881Handling the `void*` return of `bsearch`
882Common pitfalls in comparison function logic
883Generating pseudo-random numbers with `rand`
884The importance of the `RAND_MAX` constant
885Seeding the generator with `srand`
886Why you should only seed once
887Scaling `rand` results to a specific range
888Getting a unique seed with `time(NULL)`
889Getting system time with `time_t`
890Measuring intervals with `difftime`
891Breaking down time with `struct tm`
892Converting `time_t` to local time with `localtime`
893Converting `time_t` to UTC with `gmtime`
894Formatting time strings with `strftime`
895Converting `struct tm` back to `time_t` with `mktime`
896Measuring CPU ticks with `clock`
897The global `errno` variable
898Interpreting errors with `perror`
899Getting error strings with `strerror`
900Resetting `errno` before library calls
901Using `assert` for internal debugging
902Disabling assertions with `NDEBUG`
903When to use `errno` vs return codes
904Integer ranges in `limits.h`
905Using `INT_MAX` and `INT_MIN` for overflow checks
906Platform-specific character sizes
907Precision and epsilon in `float.h`
908Checking `FLT_DIG` and `DBL_DIG` for precision limits
909Managing large constants: `LONG_MAX` vs `LLONG_MAX`

840Testing for alphabetic characters with `isalpha`
841Checking for digits with `isdigit` and `isxdigit`
842Identifying whitespace with `isspace`
843Distinguishing `ispunct` and `isgraph`
844Case testing with `isupper` and `islower`
845Converting case with `toupper` and `tolower`
846The importance of casting to `unsigned char` in `ctype` functions
847Finding string length with `strlen`
848Copying strings safely with `strncpy`
849Concatenating strings with `strncat`
850Lexicographical comparison with `strcmp`
851Searching for characters with `strchr` and `strrchr`
852Finding substrings with `strstr`
853Tokenizing strings with `strtok`
854Understanding the `strcoll` and `strxfrm` locale functions
855Setting memory blocks with `memset`
856Copying memory with `memcpy`
857Handling overlapping regions with `memmove`
858Comparing memory blocks with `memcmp`
859Searching memory bytes with `memchr`
860Performance differences between `str` and `mem` functions
861Basic power and square root: `pow` and `sqrt`
862Exponential and logarithmic functions: `exp`, `log`, `log10`
863Trigonometric functions in radians
864Rounding with `ceil`, `floor`, and `round`
865Truncation and remainder: `trunc` and `fmod`
866Absolute values for floats with `fabs`
867Handling `NAN` and `INFINITY` constants
868Allocating memory with `malloc` and `free`
869Contiguous allocation with `calloc`
870Resizing blocks with `realloc`
871Converting strings to integers with `atoi` and `atol`
872Robust string-to-number conversion with `strtol`
873Converting strings to doubles with `strtod`
874Communicating with the OS using `system`
875Cleaning up at exit with `atexit`
876The generic signature of `qsort`
877Writing an integer comparison function
878Writing a string comparison function for `qsort`
879Sorting structs by multiple fields
880Using `bsearch` on sorted arrays
881Handling the `void*` return of `bsearch`
882Common pitfalls in comparison function logic
883Generating pseudo-random numbers with `rand`
884The importance of the `RAND_MAX` constant
885Seeding the generator with `srand`
886Why you should only seed once
887Scaling `rand` results to a specific range
888Getting a unique seed with `time(NULL)`
889Getting system time with `time_t`
890Measuring intervals with `difftime`
891Breaking down time with `struct tm`
892Converting `time_t` to local time with `localtime`
893Converting `time_t` to UTC with `gmtime`
894Formatting time strings with `strftime`
895Converting `struct tm` back to `time_t` with `mktime`
896Measuring CPU ticks with `clock`
897The global `errno` variable
898Interpreting errors with `perror`
899Getting error strings with `strerror`
900Resetting `errno` before library calls
901Using `assert` for internal debugging
902Disabling assertions with `NDEBUG`
903When to use `errno` vs return codes
904Integer ranges in `limits.h`
905Using `INT_MAX` and `INT_MIN` for overflow checks
906Platform-specific character sizes
907Precision and epsilon in `float.h`
908Checking `FLT_DIG` and `DBL_DIG` for precision limits
909Managing large constants: `LONG_MAX` vs `LLONG_MAX`

← C

Lesson 882 of 1,219·12. The Standard LibraryPro lesson

Common pitfalls in comparison function logic

This lesson is for subscribers

You've completed the free preview. Subscribe to unlock every lesson in every course.

See pricing Back to course