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Does strdup null terminate?
The strdup() function allocates memory and copies into it the string addressed by s1, including the terminating null character.
Does strdup need to be freed?
Because also strdup() allocates memory then it must be freed (see doc). strdup is a malloc in disguise. Reading the documentation of a standard function is faster than asking on SO ! strdup is not a Standard C function, however it is in POSIX.
What can I use instead of strdup?
Yes there is an alternative.
- get a size of string.
- create an array of the same size as is the string.
- copy the contents of the string into that array.
- point nm to your allocated array.
Is strdup thread safe?
The error value to be decoded, usually obtained from the errno global variable just before this function is called. Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.
What is strdup?
The strdup() function returns a pointer to a new string which is a duplicate of the string s. Memory for the new string is obtained with malloc(3), and can be freed with free(3). The strndup() function is similar, but copies at most n bytes.
What is returned by strdup s1?
The strdup() function shall return a pointer to a new string, which is a duplicate of the string pointed to by s1. A null pointer is returned if the new string cannot be created.
Does strdup allocate memory?
The strdup() function allocates sufficient memory for a copy of the string str , does the copy, and returns a pointer to it. The strndup() function copies at most len characters from the string str always null terminating the copied string.
How can I call malloc?
Anyway, there are a bunch of different ways for your code to legally claim some memory, including:
- Call C++ “new” operator, like “int *p=new int[10];”.
- Call the C function “malloc”, which takes a byte count and returns a pointer, like “int *p=(int *)malloc(40);”.
- Allocate space on the stack (see the next lecture).
Should I use strdup?
You should avoid strdup when writing portable code. It is trivial to implement it yourself and there is no reason to suspect that the library implementation will be much more efficient, since the optimizations lie in strlen and memcpy .
Is strdup in C99?
Most C programmers are familiar with the strdup function. Many of them will take it for granted, yet it is not part of the C Standard (neither C89, C99 nor C11). It is part of POSIX and may not be available on all environments.
What is the difference between strdup and Strcpy?
strdup allocates memory for the new string on the heap, while using strcpy (or its safer strncpy varient) I can copy a string to a pre allocated memory on either the heap or the stack.
Is the answer to strdup free or deallocate?
Actually, the answer to strdup is free of course, and the function would have been better named malloc_and_strcpy to make that clear. But many C programmers don’t think of it that way and forgets that strdup requires its opposite or “ending” free to deallocate.
When to use my _ strdup in libc?
If strdup already exists on the target platform the libc version is used, if not your custom my_strdup function will be used. EDIT: I should have added an explination why it is better. First the compiler is unrelated to the existence of a function in the libc. For example take the function strlcpy.
What does the C standard say about strdup ( )?
While this isn’t reserved, the C standard (ISO/IEC 9899:1999) section 7.26.11 (future library directions) states “Function names that begin with str, mem, or wcs and a lowercase letter may be added to the declarations in the header.” FYI: I’ve never personally seen an environment that did not define strdup ().
Why is strdup considered to be evil by Stack Overflow?
Consequently, some compilers (e.g. MSVC) discourage use (MSVC prefers _strdup ), and technically the C standard could define its own strdup with different semantics since str is a reserved prefix. So, there are some potential portability concerns with its use.