Do the return value (type ssize_t) of the C getline function and the second argument *n (type size_t) contain the same information, after invocation? Empirically, it seems that *n equals
(size_t)pow(2, ceil(log2(<return value> + 1))). Is this relation true in general? Can someone explain its (in)validity, conceptually?
C getline() function: return value vs second argument
250 Views Asked by fmg At
1
There are 1 best solutions below
Related Questions in C
- How to call a C language function from x86 assembly code?
- What does: "char *argv[]" mean?
- User input sanitization program, which takes a specific amount of arguments and passes the execution to a bash script
- How to crop a BMP image in half using C
- How can I get the difference in minutes between two dates and hours?
- Why will this code compile although it defines two variables with the same name?
- Compiling eBPF program in Docker fails due to missing '__u64' type
- Why can't I use the file pointer after the first read attempt fails?
- #include Header files in C with definition too
- OpenCV2 on CLion
- What is causing the store latency in this program?
- How to refer to the filepath of test data in test sourcecode?
- 9 Digit Addresses in Hexadecimal System in MacOS
- My server TCP doesn't receive messages from the client in C
- Printing the characters obtained from the array s using printf?
Related Questions in POINTERS
- What does: "char *argv[]" mean?
- Memory allocated for pointer to string literals
- change the value of double pointer with indirection(dereference) operator cause segmentation fault
- Unexpected result when assigning and printing pointer value of two-dimensional array with its name
- The character array data changes when I use it inside for loop. I do not understand why does it change, the data ")" becomes "("
- char * gives garbage value when pointing to a variable of a function in C
- What is correct way to copy struct instance with fields in Go?
- PHP FFI: How to pass PHP class object to C++
- How to make a single slider with three pointer
- rac dangling pointer crash。
- Is casting "pointer to array of type" to "pointer to type" defined?
- C++: How to implement a pointer to another class as a member?
- What is the purpose of (int *) p here?
- Initialize a structure pointer to NULL, then try to change its members
- Could an unitialized pointer be a NULL pointer?
Related Questions in GETLINE
- Combined usage of getline, strcat and realloc functions
- How to split using getline() in c++
- Why won't my input be displayed from an array of structure?
- Can't read past EOF in C
- eofbit not set with clear in C++98
- how to combine files and vector of class type? cpp
- sort out IP addrs from file in C program
- c++ concurrent getline on ifstream
- Using getline() when my line is split into two lines, C++
- Why does cin.getline() not read the last character when it reads my input and assigns it to a char array?
- C++ VSCode Ubuntu Terminal intercepting command line responses
- getline() reaches end of file when reading UTF-8 emoji character
- having issue with cin.getline() when working with char data type
- Process terminating with default action of signal 13 (SIGPIPE)
- How to write C++ code that takes n strings and stores them inside a vector of strings and later prints it
Related Questions in SIZE-T
- Generating hex value depending on size of size_t
- c++ how to initialize vector from variadic pack?
- int vs size_t vs long
- Does std::ranges::views::enumerate use the wrong type for indexing on GCC?
- Comparing size_t to -1
- Where is the implicit conversion that changes signedness?
- Is std::size_t a distinct type?
- Binary search algorithm using `size_t` instead of using `int`
- incompatible pointer types passing 'size_t *' (aka 'unsigned long *') to parameter of type 'int *' [-Wincompatible-pointer-types]
- Must size_t be defined using a typedef as one of the five standard unsigned integer types?
- warnings when dealing with format specifier %llu
- How do I construct a "signed size_t" for use with scanf("%zn")?
- compare between two size_t always return true when first of them is recived using %d
- C getline() function: return value vs second argument
- Difference between %zu and %lu in C
Related Questions in CSTDIO
- Clarification on fsetpos, C++
- How do right read file via stdio? C++
- Rotating two dimensional array of integers
- No console output in simple c++ program
- Not understanding the C format specifiers when using fscanf()
- std::cin unexpected behaviour on large integer input
- Inplace edit of a file using cstdio?
- C FILE* read/write and optional create
- Flush Input Buffer C
- How to set UTF-8 encoding without BOM for CStdioFileEx?
- What is fflush exactly and what does it do?
- Edit txt file using library from C
- cstdio and cstddef conflict on std::size_t
- Wrap cstdio print function with C++ variadic template
- C++ error invalid conversion from 'char' to 'const char*'
Trending Questions
- UIImageView Frame Doesn't Reflect Constraints
- Is it possible to use adb commands to click on a view by finding its ID?
- How to create a new web character symbol recognizable by html/javascript?
- Why isn't my CSS3 animation smooth in Google Chrome (but very smooth on other browsers)?
- Heap Gives Page Fault
- Connect ffmpeg to Visual Studio 2008
- Both Object- and ValueAnimator jumps when Duration is set above API LvL 24
- How to avoid default initialization of objects in std::vector?
- second argument of the command line arguments in a format other than char** argv or char* argv[]
- How to improve efficiency of algorithm which generates next lexicographic permutation?
- Navigating to the another actvity app getting crash in android
- How to read the particular message format in android and store in sqlite database?
- Resetting inventory status after order is cancelled
- Efficiently compute powers of X in SSE/AVX
- Insert into an external database using ajax and php : POST 500 (Internal Server Error)
Popular Questions
- How do I undo the most recent local commits in Git?
- How can I remove a specific item from an array in JavaScript?
- How do I delete a Git branch locally and remotely?
- Find all files containing a specific text (string) on Linux?
- How do I revert a Git repository to a previous commit?
- How do I create an HTML button that acts like a link?
- How do I check out a remote Git branch?
- How do I force "git pull" to overwrite local files?
- How do I list all files of a directory?
- How to check whether a string contains a substring in JavaScript?
- How do I redirect to another webpage?
- How can I iterate over rows in a Pandas DataFrame?
- How do I convert a String to an int in Java?
- Does Python have a string 'contains' substring method?
- How do I check if a string contains a specific word?
ssize_t getline(char **lineptr, size_t *n, FILE *stream);No. The return value is the count of characters read, not including the appended null character.
*nis the size of the current allocation of*lineptr. The return value is signed and is -1 when an (allocation) error/end-of-file occurs.*nis an unsigned type.It is expected that the return value is always less than
*n.No,
*nmay or may not be a power of 2.getline()is not part of the C standard library and implementations differ on allocation details.*n equals (size_t)pow(2, ceil(log2(<return value> + 1)))is invalid when:return value == -1
getline()does not re-allocate and the passed in size was not a power-of-2.getline()reallocates and is not using a power-of-2 scheme.Pedantic: Very large return value round down in the conversion to
doublein thelog2(_return value_ + 1)step....