Can I print null in C?
The C standard makes it undefined to pass anything other than a pointer to a null-terminated string as second argument to printf(“%s”, .
Does fprintf include null terminator?
The NUL terminator is only for fprintf (or whatever string function you are using) to know when to stop writing characters from the pointer; no NUL is actually ever written to the file.
Why is null printed in C?
First things first: printf is expecting a valid (i.e. non-NULL) pointer for its %s argument so passing it a NULL is officially undefined. It may print “(null)” or it may delete all files on your hard drive–either is correct behavior as far as ANSI is concerned (at least, that’s what Harbison and Steele tells me.)
Can fprintf fail?
The fprintf function returns the number of characters transmitted, or a negative value if an output or encoding error occurred. It would seem that given that the file is closed by the time of the second fprintf call, it should fail, but it doesn’t.
Can I print null pointer?
char* p = NULL; printf(“%s”, p); The print expects a ‘\0’ terminated array of characters (or string literal) whereas it receives a null pointer. Passing NULL to printf is undefined behavior. Take a step-up from those “Hello World” programs.
WHAT IS null pointer in C?
A Null Pointer is a pointer that does not point to any memory location. It stores the base address of the segment. The null pointer basically stores the Null value while void is the type of the pointer. A null pointer is a special reserved value which is defined in a stddef header file.
Does printf null terminate?
We have a statement like- printf(“Hello World”); Does printf append a null character after ‘d’ in the given string? No , printf does not do that in any case .
What happens if a string is not null-terminated?
If it’s not null-terminated, then it’s not a C string, and you can’t use functions like strlen – they will march off the end of the array, causing undefined behaviour. You’ll need to keep track of the length some other way.
Why is printf printing null?
By ‘undefined behavior’, one usually means ‘undefined by the standards’ right? Just asking, because the printf-source somehow interprets the zero pointer and prints out (null) ( so in the printf-source, the behavior is specified, which was the point of this comment-question).
What is null in C programming?
In computer programming, null is both a value and a pointer. Null is a built-in constant that has a value of zero. It is the same as the character 0 used to terminate strings in C. Null can also be the value of a pointer, which is the same as zero unless the CPU supports a special bit pattern for a null pointer.
What does fprintf do in C?
The function fprintf() is known as format print function. It writes and formats the output to a stream. It is used to print the message but not on stdout console.
What is the difference between fprintf and printf in C?
The C language already provides them. The difference between printf and fprintf is that printf is used to print a formatted string to a standard output which is most of the time a computer screen and fprintf is used to print a formatted string to a specific file. printf and fprintf can be used according to the task.
Is it undefined to pass Null to printf?
The print expects a ‘\\0’ terminated array of characters (or string literal) whereas it receives a null pointer. Passing NULL to printf is undefined behavior. According to Section 7.1.4 (of C99 or C11) : Use of library functions
What is the function fprintf in C library?
The C library function int fprintf (FILE *stream, const char *format.) sends formatted output to a stream.
Is it necessary to print null when passed a null pointer?
The fact that many implementations print a string such as (null) when passed a null pointer is a kindness that is dangerous to rely upon. The beauty of undefined behaviour is that such a response is permitted, but it is not required.
What’s the difference between print and printf in Java?
The print expects a ‘\\0’ terminated array of characters (or string literal) whereas it receives a null pointer. Passing NULL to printf is undefined behavior.