Why does fgets return NULL?
Why does fgets return NULL?
The fgets() function returns a pointer to the string buffer if successful. A NULL return value indicates an error or an end-of-file condition. Use the feof() or ferror() functions to determine whether the NULL value indicates an error or the end of the file. The file pointer or descriptor is not valid.
Does fgets add NULL terminator?
The fgets() function stores the result in string and adds a null character (\0) to the end of the string. The string includes the new-line character, if read.
What happens when fgets reaches end-of-file?
Upon successful completion, fgets() returns s. If the stream is at end-of-file, the end-of-file indicator for the stream is set and fgets() returns a null pointer. If a read error occurs, the error indicator for the stream is set, fgets() returns a null pointer and sets errno to indicate the error.
Why does Fopen return NULL?
It means that the file might not exist or some permission error occurred while accessing a file such as “Read-Only” or “Write-Protected”, so in those cases fopen will return 0 (a NULL pointer). On success it will return a file pointer as a handler.
Does fgets return null?
The fgets() function returns a pointer to the string buffer if successful. A NULL return value indicates an error or an end-of-file condition. Use the feof() or ferror() functions to determine whether the NULL value indicates an error or the end of the file. In either case, the value of the string is unchanged.
What is the return value of Strcmp?
The return value from strcmp is 0 if the two strings are equal, less than 0 if str1 compares less than str2 , and greater than 0 if str1 compares greater than str2 .
Does fgets read null terminate?
The fgets() function reads bytes from stream into the array pointed to by s, until n-1 bytes are read, or a newline character is read and transferred to s, or an end-of-file condition is encountered. The string is then terminated with a null byte.
What can we use instead of fgets?
getline() is another alternative for gets(). similar to fgets() , getline also reads all the input till the character delimiter (newline character)“\n” is encountered or size of the buffer. Below shows the prototype of getline(). str — This is the pointer to an array of chars where the string read is stored.
Can fgets return EOF?
2 Answers. fgets() return a null pointer when it reaches end-of-file or an error condition. ( EOF is a macro that specifies the value returned by certain other functions in similar conditions; it’s not just an abbreviation for the phrase “end of file”.) You’re ignoring the result returned by fgets() .
Which mode returns NULL if file doesn’t exist?
Mode “w”: It is a write only mode. The fopen() function creates a new file when the specified file doesn’t exist and if it fails to open file then it returns NULL. Mode “a”: Using this mode Content can be appended at the end of an existing file.
How do I know if fgets is empty?
The fgets() function stores the result in string and adds a null character (\0) to the end of the string. The string includes the new-line character, if read. If n is equal to 1, the string is empty.
Why do we test fgets for return of null-C Board?
You can input EOF to stdin, in which case fgets () will return NULL when there is nothing left to return. Someone will be along shortly with the nix equivalent. Also if more characters than BUFSIZ allows is entered into the console, do they remain in the buffer until next time we read from it?
How often does null on null input run?
The new version with the RETURNS NULL ON NULL INPUT option specified only ran 13,976 times (again, from the count of module_end events) and the CPU time for the sql_statement_completed event was 78ms with 359ms of duration.
Are there UDFs with null on null input?
I was very surprised to find out that it’s actually a form of scalar UDF optimization that has been in the product since at least SQL Server 2008 R2.
How to use null on null input in DDL?
The DDL for CREATE FUNCTION supports a WITH clause for function options and while reading the Books Online I noticed that the syntax included the following: I was really curious about the RETURNS NULL ON NULL INPUT function option so I decided to do some testing.