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.
----------------Oringinal Question------------
First I try the following somewhat direct way:
vector<char *> vec = {"Hello", "World"};
vec[0][0] = 'h';
But compiling the code I get a warning:
temp.cpp:11:43: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
vector<char *> vec = {"Hello", "World"};
^
And running the ./a.out I get a
Segmentation fault (core dumped)
I think it is because I try to write to a const char. So I try another way:
char s1[] = "Hello", s2[] = "World";
vector<char *> vec = {s1, s2};
vec[0][0] = 'h';
It is OK this time. But it seems a little tedious. Is there any other elegant way to initialize a vector with string literal?
I think the char
vs const char
difference doesn matter much in this task.
For the actual copy, use a fill constructor with iterator arguments:
vector<const char*> vc = {"hello","world"};
vector<string> vs(vc.begin(), vc.end());
See a working example.
If there's a need for editable chars in the source, just use the second version you posted:
char s1[] = "Hello", s2[] = "World";
vector<char *> vec = {s1, s2};
Supplement: The arguments of main, argc
and argv
, are a great example of
a list of char* pointers to C-style character strings
See how argc and argv get translated into a vector of string.