All Questions
39 questions
1
vote
2
answers
634
views
How can I release or move std::string::c_str()?
I have a function which interfaces with other code that creates an object from a C-string.
It goes roughly like this to build up the string before creating the object:
...
- 437
4
votes
1
answer
414
views
How to convert char* into std::u8string?
Intro
If I catch an exception, I want to convert the error message, which is returned as a C-style string by the what() method, into a std::u8string (a UTF-8 string). For example: std::u8string(error....
- 660
0
votes
1
answer
948
views
string_view Vs const char* performance
Is a std::string_view parameter better than a const char* one in the code below?
void func( const std::string_view str )
{
std::istringstream iss( str.data( ) ); // str is passed to the ctor of ...
- 3,652
0
votes
2
answers
2k
views
How can I return string as char* from a function in cpp?
for instance,
if str = "ab" is passed in a function returnString()
and we have a function defination like
string returnString(string str)
{
str+='c';
return str;
}
Output :- abc
...
5
votes
2
answers
4k
views
How to write a custom exception class derived from std::invalid_argument?
How should I write an efficient exception class to show the error that can be prevented by fixing the source code mistakes before run-time?
This is the reason I chose std::invalid_argument.
My ...
- 3,652
0
votes
1
answer
77
views
String fundamentals
So far I know the following ways to have strings in C++ (although some of these are from C)
string string1 = "Hello";
char string2[] = "Hello";
char string3[] = {'H', 'e', 'l', 'l',...
- 1,625
4
votes
1
answer
2k
views
Is there a std::string equivalent for CString::Mid()?
Is there any equivalent function in std::string for CString::mid()?
- 85
9
votes
1
answer
1k
views
Comparing std::string and C-style string literals
Suppose I have the following code:
#include <iostream>
#include <string>
#include <iomanip>
using namespace std; // or std::
int main()
{
string s1{ "Apple" };
cout <<...
- 1,589
2
votes
1
answer
450
views
Can I delete function for an rvalue version of object?
For legacy reasons, there's a lot of usage of const char* in the code I'm working on. I am trying to limit that, and stumbled on something I'd like to know. I have something like:
class AClass {
...
- 52.9k
-2
votes
2
answers
115
views
Using c-strings and std::string in the same code
I would like to know whether the following code is "valid":
#include <iostream>
using namespace std;
int main(void) {
string s="Hello World!\n";
for (int i=0;i<s.size();++i) {
...
- 11
1
vote
2
answers
1k
views
C++ creating CString from std::string fails
In my MFC based application this code:
std::string stdString("MappingName");
std::cout << "as String: " << stdString << std::endl;
CString cString(stdString.c_str());
std::cout <&...
- 993
0
votes
1
answer
346
views
Boost read_until docs
I'm pretty much a newbie to Boost in general and Boost Asio more specifically-- I've kind of been thrown into the deep end. I'm reading the Boost docs and I'm wondering if I've run into a typo in the ...
1
vote
1
answer
1k
views
Why does passing a std::string to CString.Format() only crash sometimes?
Using CString.Format(), I'm passing it a std::map that returns a std::string when given an int.
So:
CString cStr;
cStr.Format("%s", IntToStdStringMap[1]);
where IntToStdStringMap[1] returns some ...
- 185
1
vote
2
answers
391
views
How to use std::string effectively in the C-style functions which deals with conventional c-strings?
This is an old problem, which I have observed in past. So thought of getting a clarification once & for all. There are many standard / orthodox C library functions, which deal only with C-style ...
- 69.8k
1
vote
2
answers
108
views
Why is my std::string obtained via stream being overwritten?
Assume I have a function like so:
std::string get_shader(std::string path) {
std::string fullpath = "./resources/shaders/" + path;
std::ifstream vertexShaderFile(fullpath);
std::...
- 71.6k
3
votes
1
answer
1k
views
Passing the results of `std::string::c_str()` to `mkdtemp()` using `const_cast<char*>()`
OK, so: we all know that generally the use of const_cast<>() anywhere is so bad it’s practically a programming war crime. So this is a hypothetical question about how bad it might be, exactly, ...
- 4,425
11
votes
3
answers
1k
views
Default advice for using C-style string literals vs. constructing unnamed std::string objects?
So C++ 14 introduced a number of user-defined literals to use, one of which is the "s" literal suffix, for creating std::string objects. According to the documentation, its behavior is exactly the ...
- 2,834
1
vote
1
answer
1k
views
Convert string to CString
I have a string which is declared like this:
string query = "INSERT INTO tblVehicle (OVImage) VALUES ('";
query += decodedData;
query += "')";
(where 'decodedData' is a string holding Base64 data)
...
- 159
1
vote
2
answers
117
views
convert c-style-sting to std::string inside initialization list of a constructor
Is it safe to convert char* to std::string inside initialization list of a constructor like below:
class MyClass{
public:
MyClass(){}
MyClass(
char*char_Ptr_Definition_File
,char*...
- 7,896
0
votes
3
answers
537
views
Returning Char Pointer Without Heap
I was working on a program and I noticed something that didn't really make a lot of sense to me. std::string has a function called c_str() which returns a C-style string (NULL-terminated) ...
- 3,486
10
votes
3
answers
19k
views
How to elegantly initialize vector<char *> with string literal?
The problem comes from an exercise on C++ Primer 5th Edition:
Write a program to assign the elements from a list of char* pointers
to C-style character strings to a vector of strings.
-----------...
- 547
1
vote
2
answers
183
views
How to use random_shuffle with CString?
I would like to shuffle the characters present in CString varible. How do i do it?
Std provide a finction called random_shuffle() which can be used to shuffle std::string in the following way
std::...
- 63
0
votes
3
answers
7k
views
User input filename
#include <iostream>
#include <fstream>
#include <cassert>
#include <cstring>
using namespace std;
const int WL = 20;
const int WR = 1000;
void READ (ifstream &, char[], ...
- 1
0
votes
1
answer
2k
views
Conversion of CString to std::string without 'GetString()'
if m_attr.GetValue() returns a CString then:
why does the below code work without error message ... only warning message 'C4927'?
std::string sigCncDialog::GetSignalAttributeValue()
{return m_attr....
- 1,877
0
votes
3
answers
208
views
C++ variable lifetime -- need workaround to return temporary
I have a C++ object (boost::format) that has a str() function which returns an std::string.
So when I need a formatted C string, I need to write something like:
(boost::format("%1% %2%") % "1" % "2")...
- 14.3k
4
votes
2
answers
23k
views
C++: how to convert ASCII or ANSI to UTF8 and stores in std::string
My company use some code like this:
std::string(CT2CA(some_CString)).c_str()
which I believe it converts a Unicode string (whose type is CString)into ANSI encoding, and this string is for a ...
- 871
1
vote
1
answer
262
views
Compile time string assignment for run-time identification
I've been using a pattern in a library I'm creating that uses passes a String name of an object to its base object's constructor. I've tried using std::string and c-style strings but keep getting ...
- 264
0
votes
2
answers
490
views
How to construct a CString/std::string from a string position
Given the following:
for( std::string line; getline( input, line ); )
{
CString strFind = line.c_str();
int n = strFind.ReverseFind( '\\' );
CString s = CString( strFind,n );
...
- 15.7k
4
votes
3
answers
35k
views
How to convert an std::string to C-style string [duplicate]
I am programming in C++.
As basic as this question is I cannot seem to find an answer for it anywhere. So here is the problem:
I want to create a C-style string however I want to put an integer ...
- 9,347
4
votes
1
answer
760
views
How to manage string slices with less overhead?
I'm dealing with giant (up to 2GB) strings and their slices in C++ program. C-style strings seem to be unreliable under such circumstances, but can be sliced trivially (without '\0' at the end). On ...
- 15.2k
1
vote
7
answers
2k
views
std::string.c_str() has different value than std::string?
I have been working with C++ strings and trying to load char * strings into std::string by using C functions such as strcpy(). Since strcpy() takes char * as a parameter, I have to cast it which goes ...
- 1,173
2
votes
3
answers
1k
views
CString construction from std::string - copy chars or pointer
If I convert a std::string into a CString using something like:
std::string ss("Foo");
CString cs( ss.c_str() );
Does the CString copy the characters from ss or does it simply copy the char* pointer?...
- 862
25
votes
4
answers
25k
views
MFC: std::string vs CString?
Using C++ with MFC. Coming from a C# background I typically just use string for all, well, strings. I use them for class members, method parameters, and method return values.
Now in C++ I've got ...
- 65.7k
4
votes
2
answers
401
views
Is std::string a better idea than char* when you're going to have to pass it as a char*?
In a recent question, I learned that there are situations where you just gotta pass a char* instead of a std::string. I really like string, and for situations where I just need to pass an immutable ...
- 1,827
2
votes
6
answers
1k
views
What is the most efficient way to convert STL string array to const char* array?
We have:
std::string string_array[2];
string_array[0] = "some data";
string_array[1] = "some more data";
char* cstring_array[2];
What is the most efficient way to copy data from string_array ...
- 355
0
votes
1
answer
783
views
unformatted input to a std::string instead of c-string from binary file
ok i have this program working using c-strings. I am wondering if it is possible to read in blocks of unformatted text to a std::string? I toyed arround with if >> but this reads in line by ...
- 531
52
votes
4
answers
28k
views
Can a std::string contain embedded nulls?
For regular C strings, a null character '\0' signifies the end of data.
What about std::string, can I have a string with embedded null characters?
- 43k
4
votes
3
answers
5k
views
C++ difference between automatic type conversion to std::string and char*
As a learning exercise, I have been looking at how automatic type conversion works in C++. I know that automatic type conversion should generally be avoided, but I'd like to increase my knowledge of ...
- 69.3k
94
votes
16
answers
273k
views
How do you convert CString and std::string std::wstring to each other?
CString is quite handy, while std::string is more compatible with STL container. I am using hash_map. However, hash_map does not support CStrings as keys, so I want to convert the CString into a std::...
- 4,885