Reverse string c++ stl

I am preparing for an entry-level job interview. I am trying to reverse the order of words in a string, but my output is a bunch of junk that makes no sense. I think the problem may be because I'm using "char*" for my functions? Anyways, heres my code #include #include using namespace std; char* reverse(char* str, int a, int b); char* reversewords(char* str); int main() I would like to reiterate what WeaselFox said about not reinventing the wheel, try to learn the C++ STL, in the long run that will be a lot more helpful. Having said that let me suggest an approach as well. Whenever you come across problems like reversing order of chars in a string OR reversing words in a string, interviewers are really trying to test your knowledge of data structures, and in this case, specifically the "stack" data structure. Consider what happens if you parse words in a string and place them all into an array one at a time: "I AM A STRING" --> Do you see why a stack would be useful ? It's better if you reason it out yourself than I provide source code, the reason being that your approach is incorrect regardless of whether or not it yields the correct answer. I hope this helps! If you're wanting a C-like solution, you can do it with only pointers and a temp variable of type char if you need to define your own reverse function to reverse a string between two pointers. The code below simply reverses the entire string it receives (it could be modified to reverse only the string in a range...

In this tutorial, we will be discussing a program to understand different methods to reverse a string in C/C++. Example User-defined reverse() function − #include using namespace std; //function to reverse given string void reverse_str(string& str) Output tniopslairotut

Time Complexity: O(N) Auxiliary Space: O(N) 3. Using the inbuilt “reverse” Function There is a direct function in the “algorithm” header file for doing reverse that saves our time when programming. // Reverses elements in [begin, end] void reverse (BidirectionalIterator begin, BidirectionalIterator end); Output skeeGrofskeeG Complexity Analysis: Time Complexity: O(N) Auxiliary Space: O(1) How could we get the reverse of a const string? To get the reverse of a const string we have to first declare a ‘ const string’in a user-defined function following which we have declared then use the following algorithm for the calling of the desired objects. “const reverseConstString = function(string) { return string.split("").reverse().join("")” Example:

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namespace pmr (2) (since C++17) The class template basic_string stores and manipulates sequences of Traits template parameter - a specialization of Traits::char_type and CharT must name the same type; otherwise the program is ill-formed. The elements of a basic_string are stored contiguously, that is, for a basic_string s, & * (s. begin ( ) + n ) == & *s. begin ( ) + n for any n in [ ​ 0​ , s. size ( ) ) , and * (s. begin ( ) + s. size ( ) ) has value CharT ( ) (a null terminator) (since C++11); or, equivalently, a pointer to s [ 0 ] can be passed to functions that expect a pointer to the first element of an array (until C++11) a null-terminated array (since C++11) of CharT. std::basic_string satisfies the requirements of AllocatorAwareContainer (except that customized construct/ destroy are not used for construction/destruction of elements), SequenceContainer and ContiguousContainer (since C++17). Member functions of std::basic_string are constexpr: it is possible to create and use std::string objects in the evaluation of a constant expression. However, std::string objects generally cannot be constexpr, because any dynamically allocated storage must be released in the same evaluation of constant expression. (since C++20) Several typedefs for common character types are provided: Defined in header Type Definition std::string std :: basic_string std::wstring std :: basic_string std::u8string (C++20) std :: basic_string std::u16string (C++11) std :: basic_string std::u32...

The standard algorithm is to use pointers to the start / end, and walk them inward until they meet or cross in the middle. Swap as you go. Reverse ASCII string, i.e. a 0-terminated array where every character fits in 1 char. (Or other non-multibyte character sets). void strrev(char *head) • Why, yes, if the input is borked, this will cheerfully swap outside the place. • Useful link when vandalising in the UNICODE: • Also, UTF-8 over 0x10000 is untested (as I don't seem to have any font for it, nor the patience to use a hexeditor) Examples: $ ./strrev Räksmörgås ░▒▓○◔◑◕● ░▒▓○◔◑◕● ●◕◑◔○▓▒░ Räksmörgås sågrömskäR ./strrev verrts/. Non-evil C, assuming the common case where the string is a null-terminated char array: #include #include /* PRE: str must be either NULL or a pointer to a * (possibly empty) null-terminated string. */ void strrev(char *str) It's been a while and I don't remember which book taught me this algorithm, but I thought it was quite ingenious and simple to understand: char input[] = "moc.wolfrevokcats"; int length = strlen(input); int last_pos = length-1; for(int i = 0; i < length/2; i++) printf("%s\n", input); A visualization of this algorithm, courtesy of If you're looking for reversing NULL terminated buffers, most solutions posted here are OK. But, as Tim Farley already pointed out, these algorithms will work only if it's valid to assume that a string is semantically an array of bytes (i.e. single-byte strings), which is a wrong assumption, I think....

For a simple case as string x = "foobar"; you can use std::reverse(x.begin(), x.begin() + 3); // reverse the first three letters. If "foo" is embedded in the string, i.e. it is not at the start of the string, you'll have to find its location first. string x = "whoknowswhereitisfoobar"; auto loc = x.find("foo"); if ( loc != std::string::npos ) See Live Here

There are three major elements to reverse engineering C++ code that uses STL container classes: • Determining in the first place that an STL container is being used, and which category, i.e., std::list vs. std::vector vs. std::set • Determining the element type, i.e., T in the categories above • Creating data types in your reverse engineering tool of choice, and applying those types to the decompilation or disassembly listing. Though all of those elements are important, this entry focuses on the last one: creating instantiated STL data types, and more specifically, types that can be used in Hex-Rays. The main contribution of this entry is simply its underlying idea, as I have never seen it published anywhere else; the I have spent the pandemic working on a new training class on C++ reverse engineering; the images and concepts in this blog entry are taken from the class material. The class goes into much more depth than this entry, such as through material on structure and type reconstruction, and by having individual sections on each of the common STL containers. (If you are interested in the forthcoming C++ training class, it will be completed early next year, and available for in-person delivery when the world is more hospitable. If you would like to be notified when public in-person classes for the C++ course are available, please sign up on our At a language level, C++ templates are one of the most complex features of any mainstream programming language. Their introduc...

namespace pmr (2) (since C++17) The class template basic_string stores and manipulates sequences of Traits template parameter - a specialization of Traits::char_type and CharT must name the same type; otherwise the program is ill-formed. The elements of a basic_string are stored contiguously, that is, for a basic_string s, & * (s. begin ( ) + n ) == & *s. begin ( ) + n for any n in [ ​ 0​ , s. size ( ) ) , and * (s. begin ( ) + s. size ( ) ) has value CharT ( ) (a null terminator) (since C++11); or, equivalently, a pointer to s [ 0 ] can be passed to functions that expect a pointer to the first element of an array (until C++11) a null-terminated array (since C++11) of CharT. std::basic_string satisfies the requirements of AllocatorAwareContainer (except that customized construct/ destroy are not used for construction/destruction of elements), SequenceContainer and ContiguousContainer (since C++17). Member functions of std::basic_string are constexpr: it is possible to create and use std::string objects in the evaluation of a constant expression. However, std::string objects generally cannot be constexpr, because any dynamically allocated storage must be released in the same evaluation of constant expression. (since C++20) Several typedefs for common character types are provided: Defined in header Type Definition std::string std :: basic_string std::wstring std :: basic_string std::u8string (C++20) std :: basic_string std::u16string (C++11) std :: basic_string std::u32...

There are three major elements to reverse engineering C++ code that uses STL container classes: • Determining in the first place that an STL container is being used, and which category, i.e., std::list vs. std::vector vs. std::set • Determining the element type, i.e., T in the categories above • Creating data types in your reverse engineering tool of choice, and applying those types to the decompilation or disassembly listing. Though all of those elements are important, this entry focuses on the last one: creating instantiated STL data types, and more specifically, types that can be used in Hex-Rays. The main contribution of this entry is simply its underlying idea, as I have never seen it published anywhere else; the I have spent the pandemic working on a new training class on C++ reverse engineering; the images and concepts in this blog entry are taken from the class material. The class goes into much more depth than this entry, such as through material on structure and type reconstruction, and by having individual sections on each of the common STL containers. (If you are interested in the forthcoming C++ training class, it will be completed early next year, and available for in-person delivery when the world is more hospitable. If you would like to be notified when public in-person classes for the C++ course are available, please sign up on our At a language level, C++ templates are one of the most complex features of any mainstream programming language. Their introduc...